Where is zone 5?

Sunset climate zones: Central California

To view detailed maps, click the “Click to Enlarge” button at left.

ZONE 1A: Coldest mountain and intermountain areas of the contiguous states

Marked by a short growing season and relatively mild summer temperatures, Zone 1A includes the coldest regions west of the Rockies, excluding Alaska, and a few patches of cold country east of the Great Divide. The mild days and chilly nights during the growing season extend the bloom of summer perennials like columbines and Shasta daisies. If your garden gets reliable snow cover (which insulates plants), you’ll be able to grow perennials listed for some of the milder zones. In years when snow comes late or leaves early, protect plants with a 5- or 6-inch layer of organic mulch. Along with hardy evergreen conifers, tough deciduous trees and shrubs form the garden’s backbone. Gardeners can plant warm-season vegetables as long as they are short-season varieties. To further assure success, grow vegetables from seedlings you start yourself or buy from a nursery or garden center. Winter lows average in the 0 to 11°F (–18 to –12°C) range; extremes range from –25 to –50°F (–32 to –46°C). The growing season is 50 to 100 days.

ZONE 2A: Cold mountain and intermountain areas

Another snowy winter climate, Zone 2A covers several regions that are considered mild compared with surrounding climates. You’ll find this zone stretched over Colorado’s northeastern plains, a bit of it along the Western Slope and Front Range of the Rockies, as well as mild parts of river drainages like those of the Snake, Okanogan, and the Columbia. It also shows up in western Montana and Nevada and in mountain areas of the Southwest. This is the coldest zone in which sweet cherries and many apples grow. Winter temperatures here usually hover between 10 and 20°F (–12 to –7°C) at night, with drops between –20 and –30°F (–29 and –34°C) every few years.When temperatures drop below that, orchardists can lose even their trees. The growing season is 100 to 150 days.

ZONE 3A: Mild areas of mountain and intermountain climates

East of the Sierra and Cascade ranges, you can hardly find a better gardening climate than Zone 3a.Winter minimum temperatures average from 15 to 25°F (–9 to –4°C), with extremes between –8 and –18°F (–22 and –28°C). Its frost-free growing season runs from 150 to 186 days. The zone tends to occur at lower elevations in the northern states (eastern Oregon and Washington as well as Idaho), but at higher elevations as you move south crossing Utah’s Great Salt Lake and into northern New Mexico and Arizona. Fruits and vegetables that thrive in long,warm summers, such as melons, gourds, and corn, tend to do well here. This is another great zone for all kinds of deciduous fruit trees and ornamental trees and shrubs. Just keep them well watered.

ZONE 7: California’s Gray Pine Belt, Oregon’s Rogue River Valley, and Southern California mountains

Zone 7 encompasses several thousand square miles west of the Sierra Nevada and Cascade ranges, and in the mountains that separate the Southern California coast from interior deserts. Because of the influence of latitude, this climate lies mostly at low elevations in Oregon’s Rogue Valley, middle elevations around California’s Central Valley, and at middle to higher elevations farther south. Gray pines define the heart of Zone 7 around the Central Valley, but more adaptable incense cedars replace them farther north and south.

Hot summers and mild but pronounced winters give Zone 7 sharply defined seasons without severe winter cold or enervating humidity. The climate pleases plants that require a marked seasonal pattern to do well—flower bulbs, peonies, lilacs, and flowering cherries, for example. Deciduous fruit trees do well also; the region is noted for its pears, apples, peaches, and cherries.

Gardeners in a few spots around the San Francisco Bay will be surprised to find their gardens mapped in Zone 7. These areas are too high and cold in winter to be included in milder Zones 15 and 16. In the mildest parts of Zone 7—in the extreme southern Salinas Valley, for example—you can get away with growing borderline plants such as citrus, oleanders, and almonds if you choose a spot with good air drainage to take the edge off winter chill. At weather-recording stations in Zone 7, typical winter lows range from 35 to 26°F (2 to –3°C),with record lows averaging from 18 to -0° F (–8 to –18°C).

ZONE 8: Cold-air basins of California’s Central Valley

Zone 8 makes up most of the valley floor in California’s Sacramento and San Joaquin Valleys. Only a shade of difference exists between Zone 8 and Zone 9, but it’s an important difference—crucial in some cases. Zone 9 is a thermal belt,meaning that cold air can flow from it to lower ground—and that lower ground is found here in Zone 8. Citrus furnish the most meaningful illustration. Lemons, oranges, and grapefruit, which flourish in Zone 9, cannot be grown commercially in Zone 8 because the winter nights are frequently cold enough to injure the fruit or the trees; the trees would need regular heating to deliver decent crops. The same winter cold can damage many garden plants. That cold often shows itself in winter, when cold air rolls off the Sierra Nevada and pools on the valley floor, condensing into thick tule fog. Zone 8 differs from Zone 14, which it joins near the latitudes of north Sacramento and Modesto, in that Zone 14 occasionally gets some marine influence. Low temperatures in Zone 8 over a 20-year period ranged from 29 to 13°F (–2 to –11°C). Certain features that Zones 8 and 9 share are described under Zone 9.

ZONE 9: Thermal belts of California’s Central Valley

As cited in the description of Zone 8, the biggest readily apparent difference between Zones 8 and 9 is that Zone 9, a thermal belt, is a safer climate for citrus than Zone 8, which contains cold-air basins. The same distinction, thermal belt versus cold-air basin, determines which species and varieties—hibiscus,melaleuca, pittosporum, and other plants—are recommended for Zone 9 but not for Zone 8. Zones 8 and 9 have the following features in common: summer daytime temperatures are high, sunshine is almost constant during the growing season, and growing seasons are long.Deciduous fruits and vegetables of nearly every kind thrive in these long, hot summers; winter cold is just adequate to satisfy the dormancy requirements of the fruit trees. Fiercely cold, piercing north winds blow for several days at a time in winter, but they are more distressing to gardeners than to garden plants.You can minimize them with windbreaks. In both Zones 8 and 9 tule fogs (dense fogs that rise from the ground on cold, clear nights) appear and stay for hours or days during winter. The fogs usually hug the ground at night and rise to 800 to 1,000 feet by afternoon. Heat-loving plants such as oleander and crape myrtle perform at their peak in Zones 8 and 9 (and 14). Plants that like summer coolness and humidity demand some fussing; careful gardeners accommodate them by providing filtered shade from tall trees and plenty of moisture. In Zone 9,winter lows over a 20-year period ranged from 28 to 18°F (–2 to –8°C).

ZONE 14: Northern California’s inland areas with some ocean influence

Marine air moderates parts of Zone 14 that otherwise would be colder in winter and hotter in summer. The opening in Northern California’s Coast Ranges created by San Francisco and San Pablo bays allows marine air to spill much farther inland. The same thing happens, but the penetration is not as deep, in the Salinas Valley. Zone 14 includes the cold-winter valley floors, canyons, and land troughs in the Coast Ranges from Santa Barbara County to Humboldt County.

The milder-winter, marine-influenced areas in Zone 14 and the cold-winter inland valley within Zone 14 differ in humidity. For example, lowland parts of Contra Coasta County are more humid than Sacramento.

Fruits that need winter chill do well here, as do shrubs needing summer heat (oleander, gardenia). Over a 20-year period, this area had lows ranging from 26 to 16º F (–3 to –9ºC). Weather records show all-time lows from 20 down to 11ºF (–7 to –12º C).

ZONE 15: Chilly winters along the Coast Range

Zones 15 and 16 are areas of Central and Northern California that are influenced by marine air approximately 85 percent of the time and by inland air 15 percent of the time.Also worthy of note is that although Zone 16 is within the Northern California coastal climate area, its winters are milder because the areas in this zone are in thermal belts (explained on page 28). The cold-winter areas that make up Zone 15 lie in cold-air basins, on hilltops above the thermal belts, or far enough north that plant performance dictates a Zone 15 designation. Many plants that are recommended for Zone 15 are not suggested for Zone 14 mainly because they must have a moister atmosphere, cooler summers, milder winters, or all three conditions present at the same time. On the other hand, Zone 15 still receives enough winter chilling to favor some of the coldwinter specialties, such as English bluebells, which are not recommended for Zones 16 and 17. Most of this zone gets a nagging afternoon wind in summer. Trees and dense shrubs planted on the windward side of a garden can disperse it, and a neighborhood full of trees can successfully keep it above the rooftops. Lows over a 20-year period ranged from 28 to 21°F (–2 to –6°C), and record lows from 26 to 16°F (–3 to –9°C).

ZONE 16: Central and Northern California Coast thermal belts

This benign climate exists in patches and strips along the Coast Ranges from western Santa Barbara County north to northern Marin County. It’s one of Northern California’s finest horticultural climates. It consists of thermal belts (slopes from which cold air drains) in the coastal climate area, which is dominated by ocean weather about 85 percent of the time and by inland weather about 15 percent. Typical lows in Zone 16 over a 20-year period ranged from 32 to 19°F (0 to –7°C). The lowest recorded temperatures range from 25 to 18°F (–4 to –8°C). This zone gets more heat in summer than Zone 17, which is dominated by maritime air, and has warmer winters than Zone 15. That’s a happy combination for gardening. A summer afternoon wind is an integral part of this climate. Plant trees and shrubs on the windward side of your garden to help disperse it.

ZONE 17: Marine effects in Southern Oregon, Northern and Central California

The climate in this zone features mild,wet, almost frostless winters and cool summers with frequent fog or wind. On most days and in most places, the fog tends to come in high and fast, creating a cooling and humidifying blanket between the sun and the earth, reducing the intensity of the light and sunshine. Some heat-loving plants (citrus, hibiscus, gardenia) don’t get enough heat to fruit or flower reliably. In a 20-year period, the lowest winter temperatures in Zone 17 ranged from 36 to 23°F (2 to –5°C). The lowest temperatures on record range from 30 to 20°F (–1 to –7°C).Of further interest in this heat-starved climate are the highs of summer, normally in the 60 to 75°F (16 to 24°C) range. The average highest temperature in Zone 17 is only 97°F (36°C). In all the other adjacent climate zones, average highest temperatures are in the 104 to 116°F (40 to 47°C) range.

ZONE 18: Above and below the thermal belts in Southern California’s interior valleys

Zones 18 and 19 are classified as interior climates. This means that the major influence on climate is the continental air mass; the ocean determines the climate no more than 15 percent of the time. Many of the valley floors of Zone 18 were once regions where apricot, peach, apple, and walnut orchards flourished, but the orchards have now given way to homes.Although the climate supplies enough winter chill for some plants that need it, it is not too cold (with a little protection) for many of the hardier subtropicals like amaryllis. It is too hot, too cold, and too dry for fuchsias but cold enough for tree peonies and many apple varieties, and mild enough for a number of avocado varieties. Zone 18 never supplied much commercial citrus, but home gardeners who can tolerate occasional minor fruit loss can grow citrus here. Over a 20-year period,winter lows averaged from 22 to 17°F (–6 to –8°F).The all-time lows recorded by different weather stations in Zone 18 ranged from 22 to 7°F (–6 to –14°C).

ZONE 19: Thermal belts around Southern California’s interior valleys

Like that of neighboring Zone 18, the climate in Zone 19 is little influenced by the ocean. Both zones, then, have very poor climates for such plants as fuchsias, rhododendrons, and tuberous begonias. Many sections of Zone 19 have always been prime citrus-growing country—especially for those kinds that need extra summer heat in order to grow sweet fruit. Likewise, macadamia nuts and most avocados can be grown here. The Western Plant Encyclopedia cites many ornamental plants that do well in Zone 19 but are not recommended for its neighbor because of the milder winters in Zone 19. Plants that grow well here, but not in much colder zones, include bougainvillea, bouvardia, calocephalus, Cape chestnut (Calodendrum), flame pea (Chorizema), several kinds of coral tree (Erythrina), livistona palms, Mexican blue and San Jose hesper palms (Brahea armata, B. brandegeei), giant Burmese honeysuckle (Lonicera hildebrandiana), myoporum, several of the more tender pittosporums, and lady palm (Rhapis excelsa). Extreme winter lows over a 20-year period ranged from 28 to 22°F (–2 to –6°C) and the all-time lows at different weather stations range from 23 to 17°F (–5 to –8°C). These are considerably higher than the temperatures in neighboring Zone 18.

ZONE 20: Cool winters in Southern California’s areas of occasional ocean influence

In Zones 20 and 21, the same relative pattern prevails as in Zones 18 and 19. The even-numbered zone is the climate made up of cold-air basins and hilltops, and the odd-numbered one comprises thermal belts. The difference is that Zones 20 and 21 get weather influenced by both maritime air and interior air. In these transitional areas, climate boundaries often move 20 miles in 24 hours with the movements of these air masses. Because of the greater ocean influence, this climate supports a wide variety of plants.You can see the range of them at the Los Angeles County Arboretum in Arcadia. Typical winter lows are 37° to 43°F (3 to 6°C); extreme 20-year lows average from 25 to 22°F (–4 to –6°C).Alltime record lows range from 21 to 14°F (–6 to –10°C).

ZONE 21: Thermal belts in Southern California’s areas of occasional ocean influence

The combination of weather influences described for Zone 20 applies to Zone 21 as well. Your garden can be in ocean air or a high fog one day and in a mass of interior air (perhaps a drying Santa Ana wind from the desert) the next day. Because temperatures rarely drop very far below 30°F (–1°C), this is fine citrusgrowing country. At the same time, Zone 21 is also the mildest zone that gets sufficient winter chilling for most forms of lilacs and certain other chill-loving plants. Extreme lows—the kind you see once every 10 or 20 years—in Zone 21 average 28 to 25°F (–2 to –4°C).All-time record lows in the zone were 27 to 17°F (–3 to –8°C).

ZONE 22: Cold-winter portions of Southern California’s coastal climate

Areas falling in Zone 22 have a coastal climate (they are influenced by the ocean approximately 85 percent of the time).When temperatures drop in winter, these cold-air basins or hilltops above the air-drained slopes have lower winter temperatures than those in neighboring Zone 23. Actually, the winters are so mild here that lows seldom fall below freezing. Extreme winter lows (the coldest temperature you can expect in 20 years) average 28 to 25°F (–2 to –4°C). Gardeners who plant under overhangs or tree canopies can grow subtropical plants that would otherwise be burned by a rare frost. Such plants include bananas, tree ferns, and the like. The lack of a pronounced chilling period during the winter limits the use of such deciduous woody plants as flowering cherry and lilac. Many herbaceous perennials from colder regions fail here because the winters are too warm for them to go dormant.

ZONE 23: Thermal belts of Southern California’s coastal climate

One of the most favored areas in North America for growing subtropical plants, Zone 23 has always been Southern California’s best zone for avocados. Frosts don’t amount to much here, because 85 percent of the time, Pacific Ocean weather dominates; interior air rules only 15 percent of the time. A notorious portion of this 15 percent consists of those days when hot, dry Santa Ana winds blow. Zone 23 lacks either the summer heat or the winter cold necessary to grow pears,most apples, and most peaches. But it enjoys considerably more heat than Zone 24—enough to put the sweetness in ‘Valencia’ oranges, for example—but not enough for ‘Washington’ naval oranges, which are grown farther inland. Temperatures are mild here, but severe winters descend at times.Average lows range from 43 to 48°F (6 to 9°C), while extreme lows average from 34 to 27°F (1 to –3°C).

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New USDA Plant Hardiness Zone Map released

By Kathryn Sarkis


In January the USDA released an updated Plant Hardiness Zone Map (PHZM). The PHZM splits the county in multiple climate zones and is used by gardeners to determine what plants will thrive in their location. The new map represents the first update since 1990 and is designed specifically to provide greater detail to the internet user. The map was created using GIS technology, and therefore is much more complete and accurate than the previous PHZM.

To the casual observer the map creates a compelling case for climate change, as each zone is now about half-a-zone warmer than previous version. The USDA, however, cautions against this conclusion. This map only incorporates 30 years of weather data, rather than 50 – 100 years of data needed to establish climate trends; furthermore, this map was created with more sophisticated mapping methods. So we can’t really compare it against previous versions. It is important to note, however, that according to NOAA, the top 10 warmest years on record have been since 1990, and this data is captured in the new PHZM map.

A better map for looking at warming trends in relation to plant hardiness comes from a map published in 2006 by The Arbor Day Foundation. They used the same techniques as the PHZM, and created a compelling animated graphic showing what the changes look like over time. The graphic shows warmer zones migrating north from 1990 to 2006, and here the change seems pretty significant.

While the USDA maintains the change in zones is not evidence of “climate change,” that geopolitical thing we are not allowed to talk about in polite company. Nonetheless, it reveals that our climate is… well… changing. Take for example Sacramento, California, where most zip codes shifted from zone 9 to zone 9b. While all of zone 9 is in danger of a frost, zone 9a’s low temperature is 20 degrees while zone 9b’s low is from 25-30 degrees. In practical terms this shift means that Sacramento residents can now plant avocado trees which will likely survive in zone 9b, but have very little chance in zone 9a.

I do not have a long enough history in my own garden to discern any subtle shifts in bloom patterns or types of plants I can grow, so I cannot offer any personal notes on what I have noticed. I do know that I enjoy spending time in my garden and watching it shift each season, and I am excited to see how it matures. To keep my gardening footprint low I am going to follow The Union for Concerned Scientists suggestions for climate friendly gardening.

What is happening in your garden? Have you been there long enough to notice any trends?

Take the first step.

Start small. Be conscious of the impact your actions have on the environment and figure out what you can do to lessen the blow. Calculate, conserve, and offset.

For businesses, our Corporate Sustainability Plans can help you with your emission reduction goals.

USDA Hardiness Zone Map gets update

“One of the driving factors was to make the map state of the art,” she said. ” We wanted a map that would better serve its users.”

Locating a growing zone on the online map (www.planthardiness.ars.usda.gov) is done by typing in a ZIP code. The previous method was to eyeball a 4-foot-by-4-foot poster of the United States covered with colorful swirls. In regions of the country with sameness to the weather (think Kansas) that worked. But for the north state, where weather is as varied as the topography, finding a growing zone or even pinpointing Redding’s location on the wordless map with merging and converging colors was tricky.

Kaplan gave it a go. Using a California map with the previous Hardiness Zone Map, she attempted to determine the north state’s plant hardiness zones.

“You were, in the western part of Shasta (County), 8B. Then there’s a nice big lump that looks like 9A ? a nice big swath, and then it starts climbing again. There’s a swath of 8B and 8A, 7B and 7A,” she said.

She added: “My eyes are beginning to roll. I’ve been doing this for reporters all over the country.”

Bottom line: Zone location was not an exact science. The old map was confusing for north state gardeners, said Leimone Waite, horticulture instructor at Shasta College.

“If you are looking at absolutely downtown Redding, that was Zone 9, but often as you got into the outlying areas you were going into Zone 7,” she said.

The new map’s ZIP code feature is straightforward. It shows the 96001 and 96003 areas of Redding in Zone 9B with average annual winter lows of 25 to 30 degrees. Palo Cedro, Anderson and the 96002 area of Redding are 9A, 20 to 25 degrees.

The zones are based only on winter lows and the temperature ranges are averages, not how cold a place has ever been or ever will be.

The new map is built on 30 years of weather records, Kaplan said. The previous map used 13 years of data. The new map makes use of Geographic Information System technology. An algorithm factored in the effects of slope, elevation and large bodies of water on temperatures, Kaplan said.

Much of the country ended up in warmer zones. But Kaplan said the map shouldn’t be used as a measure of global climate change. Climatologists consider high temperatures as well as lows and look at records over a much longer time period, she said.

Because the new map relied on more data and newer technology, it’s not surprising that there were changes, Kaplan said. “It’s very had to compare the 1990 map and the new map. The 2012 map is so much more sophisticated. You are really comparing apples and oranges.”

Hardiness zones help gardeners find plants that fit the conditions in their yards. A plant label that says, “Hardy to Zone 10,” lets a shopper know if the plant would a good match.

“The hardiness zones are a common vocabulary by which gardeners and those who breed and grow plants for them can communicate,” Kaplan said.

Waite said north state gardeners seem to pay more attention to the zones in “Sunset Western Garden Book.” Its close-up maps show cities and take into consideration high temperatures, topography, soil and other factors.

“I think most people in California tend to use the Sunset zones more, but the problem with that is that most catalogs or nursery descriptions use the USDA zones,” Waite said.

Hardiness zones are important to those gardeners who push the boundaries, she said.

“Some of us have zonal envy. If you are looking to grow things that are marginal in your zone, then I think in those cases people do pay close attention,” she said.

A growing zone is not the final word on survivability. Within zones ? even within a backyard ? there can be microclimates.

“There are those little banana belts that go through some of the areas around here,” said Doug Campbell, owner of Gold Leaf Nursery in Redding.

“All hardiness zone maps, even one as sophisticated and accurate as this one, are only guides,” Kaplan said. “Nothing supplants a gardener’s knowledge of his or her garden.”

Hardiness zones are guides, not guarantees.

Many plant species slowly acquire hardiness in the fall as days grow shorter and temperatures become cooler. The hardiness is lost gradually in late winter when days get longer. Timing of cold weather has a big impact on plant damage. A blast of cold in early fall can injure plants that haven’t had time to toughen up even if the temperature isn’t extremely cold. Exceptionally warm weather in midwinter followed by sudden change to cold also can injure plants.

Hardiness zones are based on average low temperatures, not the lowest temperature ever recorded. An extreme cold snap can kill plants that have thrived for years.

Hardiness zones are one part of the gardening picture. Soil, moisture, exposure and other factors also contribute to the success or failure of plants.

Source: USDA Agricultural Research Service

Micro Climates of Costa Rica

Mal País Sunset & Surf

Abundant in lush tropical rainforests, spectacular sunbathed beaches and a wide array of plant and animal species, Costa Rica is blessed with incredibly diverse micro climates.

The great variety in climates is mainly due to the geographical diversity. Being closer to the equator, it has been classified as a tropical country.

However with its own distinct climatic zones it has a lot to offer in terms of weather.

Best Hotels in Costa Rica Price

12 Climatic Zones

Located in the tropics, Costa Rica has twelve climatic zones varying from hot and humid to cold and frosty.

The temperatures are mostly determined by the elevation and other geographical factors.

There are two major seasons that exist in this tropical paradise, these being the dry season (lasting from December to April) and the rainy season (from May to November).

Costa Rica’s micro climates vary from the exotic volcanoes to the cool cloud forests, from the dense jungle to the tropical dry forests and golden beaches to the secluded waterfalls and rivers.

The overall climate of Costa Rica can be described as mild. Located within the tropics, it is prone to drastic seasonal changes. The temperatures during the dry season remain pleasantly in the high 80 degrees F while during the wet season the mornings may be sunny and showers are expected in the afternoons.

The coastal areas have slightly higher temperatures while the mountain ranges are colder and temperatures may even drop down to the low 50 degrees F.

Temperatures usually vary from 70 degrees F in the Central region to high 80’s in the Northern lowlands and in the low 80’s near the Caribbean coast.

Coolest temperatures have been recorded as low as 40 degrees F. On average the hottest months in Costa Rica are February to April while the coolest are September through November, with a great contrast in temperatures during the night and day. Of course these are averages and this greatly varies on location.

Look at our Costa Rica weather chart to see the specifics on the time and location for the best times to travel.

Rainfall in Costa Rica

Rain also varies from region to region. Costa Rica receives an average rainfall of 100 inches per year.

The Caribbean coastline is the most humid while the Northern lowlands are the driest.

Some areas like the Guanacaste province receive very low amount of rain.

The weather ranges from dry to humid, from hot to rainy with sunshine to light tropical breeze and rainbows with occasional pelo de gato.

With such an array of temperatures to offer, it is necessary to keep the varying weather in mind while travelling in Costa Rica.

There are two zone maps to consider when planning your Sacramento landscape: the USDA hardiness zone and the Sunset climate zone.

USDA Zone Map

The USDA zone map is based off of winter low temperatures.

As you can see from the map, zone 9 dominates the Sacramento area. Plants recommended for zone 9 should survive our mild winters.

Sunset Zone Map

Sunset zone maps take things a step further and depending on whether your are landscaping in Sacramento itself, or up toward the hills, your zone may be either 14 or 9.

Sunset climate zones take mulitple factors into consideration to ensure that plants don’t simply survive, but thrive!

ZONE 9: Thermal belts of California’s Central Valley

As cited in the description of Zone 8, the biggest readily apparent difference between Zones 8 and 9 is that Zone 9, a thermal belt, is a safer climate for citrus than Zone 8, which contains cold-air basins. The same distinction, thermal belt versus cold-air basin, determines which species and varieties—hibiscus,melaleuca, pittosporum, and other plants—are recommended for Zone 9 but not for Zone 8. Zones 8 and 9 have the following features in common: summer daytime temperatures are high, sunshine is almost constant during the growing season, and growing seasons are long.Deciduous fruits and vegetables of nearly every kind thrive in these long, hot summers; winter cold is just adequate to satisfy the dormancy requirements of the fruit trees. Fiercely cold, piercing north winds blow for several days at a time in winter, but they are more distressing to gardeners than to garden plants.You can minimize them with windbreaks. In both Zones 8 and 9 tule fogs (dense fogs that rise from the ground on cold, clear nights) appear and stay for hours or days during winter. The fogs usually hug the ground at night and rise to 800 to 1,000 feet by afternoon. Heat-loving plants such as oleander and crape myrtle perform at their peak in Zones 8 and 9 (and 14). Plants that like summer coolness and humidity demand some fussing; careful gardeners accommodate them by providing filtered shade from tall trees and plenty of moisture. In Zone 9,winter lows over a 20-year period ranged from 28 to 18°F (–2 to –8°C).

ZONE 14: Northern California’s inland areas with some ocean influence

Marine air moderates parts of Zone 14 that otherwise would be colder in winter and hotter in summer. The opening in Northern California’s Coast Ranges created by San Francisco and San Pablo bays allows marine air to spill much farther inland. The same thing happens, but the penetration is not as deep, in the Salinas Valley. Zone 14 includes the cold-winter valley floors, canyons, and land troughs in the Coast Ranges from Santa Barbara County to Humboldt County.

The milder-winter, marine-influenced areas in Zone 14 and the cold-winter inland valley within Zone 14 differ in humidity. For example, lowland parts of Contra Coasta County are more humid than Sacramento.

Fruits that need winter chill do well here, as do shrubs needing summer heat (oleander, gardenia). Over a 20-year period, this area had lows ranging from 26 to 16º F (–3 to –9ºC). Weather records show all-time lows from 20 down to 11ºF (–7 to –12º C).

Northern CA Sunset Zones

California Energy Maps

List of All Energy Maps

California Building Climate Zone Areas

Climate Zone Search App

The Energy Commission has developed the below app to quickly and accurately show addresses and locations in relation to the geographic meets and bounds that determine California’s climate regions. We invite builders and building officials to use this app to determine the climate zones applicable to building projects.

  • EZ Building Climate Zone Search App
  • Instructions for Search App

Climate Zone Area Maps:
(Updated November 2017)

California Building Climate Zone Areas (Acrobat PDF)

California Building Climate Zone Areas (Google Earth KMZ)
Google Earth is required to open KMZ files. It can be downloaded for free at: www.google.com/earth/

List of Climate Zone Areas by ZIP Code:
(Updated )

Climate Zones by ZIPcode List (Acrobat PDF)

Climate Zones by ZIPcode List (MS Excel)

Climate Zone Weather Data:

California Weather Data

For more information regarding the climate zone map, please refer to the Title 24 Standards or contact the Title 24 Energy Efficiency Standards Hotline at:

E-mail: [email protected]
916-654-5106
800-772-3300 (toll free in California)

Please Note:

The numbers used in the climate zone map don’t have a title or legend. The California climate zones shown in this map are not the same as what we commonly call climate areas such as “desert” or “alpine” climates. The climate zones are based on energy use, temperature, weather and other factors.

This is explained in the Title 24 energy efficiency standards glossary section:

“The Energy Commission established 16 climate zones that represent a geographic area for which an energy budget is established. These energy budgets are the basis for the standards….” “(An) energy budget is the maximum amount of energy that a building, or portion of a building…can be designed to consume per year.”

“The Energy Commission originally developed weather data for each climate zone by using unmodified (but error-screened) data for a representative city and weather year (representative months from various years). The Energy Commission analyzed weather data from weather stations selected for (1) reliability of data, (2) currency of data, (3) proximity to population centers, and (4) non-duplication of stations within a climate zone.

“Using this information, they created representative temperature data for each zone. The remainder of the weather data for each zone is still that of the representative city.” The representative city for each climate zone (CZ) is:

CZ 1: Arcata
CZ 2: Santa Rosa
CZ 3: Oakland
CZ 4: San Jose-Reid
CZ 5: Santa Maria
CZ 6: Torrance
CZ 7: San Diego-Lindbergh
CZ 8: Fullerton
CZ 9: Burbank-Glendale
CZ10: Riverside
CZ11: Red Bluff
CZ12: Sacramento
CZ13: Fresno
CZ14: Palmdale
CZ15: Palm Spring-Intl
CZ16: Blue Canyon

The original detailed survey definitions of the 16 Climate Zones are found in the 1995 publication, “California Climate Zone Descriptions for New Buildings.”
(PDF file, 178 pages, 9.7 MB)

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