Climate Zones of the Mid Klamath-Trinity Region
The Mid Klamath region encompasses a wide array of elevations, soils and topography that have given rise to one of the most diverse flora and fauna of any temperate zone on earth. This same complexity yields a range of opportunities and challenges for farming and gardening. It is possible to grow fresh produce year round on low elevation valley floors and river bars, while higher elevations and north facing drainages are some of the coldest climate zones in the West. Banana belts offer microclimates that escape frosts, extending the growing season by many weeks on some sites.
Identifying your climate zone and microclimates will help clarify the challenges and opportunities of gardening in your area and provide a way to adapt information to your specific site. Most of the charts and calendars listed on this website are based on Sunset climate zone 14, which includes the lower elevations of Orleans, Hoopa Valley and Willow Creek. If you live in a cooler climate zone, such as Happy Camp or Seiad Valley (Sunset zone 7), you will need to adjust the information accordingly. Most gardeners are familiar with the USDA climate zones that reference a plants hardiness (or tolerance to cold). The climate zones developed by Sunset Gardening are much more detailed and are a better resource for our area. However, since most plant tags reference the USDA zones, we have included it as an additional reference.
Sunset Climate Zones of the Klamath-Trinity
The climate zones listed here developed by Sunset Gardening are far more detailed than USDA climate zones, taking into account factors such as frost-free days, humidity, prevailing winds, effects of ocean, elevation and regional weather patterns. (USDA climate zones are based only on annual average minimum temperature). These climate zones paint a fuller picture of our regional climate and are much more useful for describing and comparing climate in our area. Identifying your climate zone will clarify opportunities and challenges in your region and help in adjusting dates for planting, harvesting etc.
Sunset ZONE 14: Orleans, Weitchpec, Hoopa, Willow Creek. Northern California's inland areas with some ocean influence
The marine air that spills inland via the Klamath and Trinity canyons moderates has a strong influence on this climate zone, delineating it's boundaries. Summer temperatures climb regularly into the triple digits in this area, producing some of the earliest tomatoes and peaches at the coastal farmers markets. The valley floors in this area are subject to hard winter frosts. There can be a 50 degree temperature swing between daytime highs and nighttime lows, a phenomenon that builds complex flavors an character in tree fruit and wine grapes. Crops that require lots of heat (i.e. peaches, tomatoes, peppers, eggplants, figs,) or lots or cold (i.e. fruit trees that require winter chill) do well here. Fruit trees and berries that do not do well with extreme heat, such as apples, filberts, blueberries, benefit from being planted where afternoon shade provides relief from the most intense heat. A long growing season means year round gardening. Clear, dry spells in the winter can lead to a pattern of hard frosts that can be hard on winter gardens. 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: Inland Slopes of the Coast Range and Siskiyous, from Willow Creek to Orleans, with Marine Influence.
Head west from route 96 on a hot summer day on any of the roads that climb steeply from the Klamath River Canyon and you're liable to encounter coastal fog that spills over the mountains and gives rise to a dense forest that includes coastal species such as rhododendron, azalea, salal and Port Orford Cedar. The slope and coastal influence tempers the extremes of summer heat and winter chill found at the valley floors for the Klamath and Trinity. 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. 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. 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).
Sunset ZONE 7: North of Somes Bar, Salmon River Lower Elevations, Happy Camp, Seiad Valley, inland areas with diminishing coastal influence; California’s Gray Pine Belt.
The "river fog" that creeps up the Klamath from the coast typically makes it no farther than Somes Bar, marking the transition between zone 14 and Zone 7. Zone 7 is named for the Gray pines that rim the mid elevation around the Central Valley, in our region mingled with more adaptable incense cedars. Average temperatures are lower than zone 14, the occasional snow that reaches the lower elevations of the Mid Klamath are likely to stick around a bit longer here. Microclimates can make a big difference for gardening - south and west aspects with some elevation are markedly warmer and enjoy more frost free days. This is an ideal climate for plants that require a marked seasonal pattern—flower bulbs, peonies, lilacs, and flowering cherries, for example. Deciduous fruit trees (apples, pears, apples, peaches, and cherries) do well. 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 1A: Coldest high elevation areas of the Mid Klamath
Climb high enough in the Mid Klamath and eventually you hit the coldest climate zone where extended low winter temperatures are the most limiting factor, shortening the growing season and ruling out any plants that are not frost hardy. 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 4: Mid to High Elevations of the Mid Klamath, areas with Cold Winters
As one gains elevation in the Mid Klamath the growing season shortens due to late Spring and early Fall frost, and more snow in the winter. One of the West’s most narrow, linear climates, Zone 4 runs from high in the coastal mountains of Northern California to southeastern Alaska, losing elevation as it moves north. It gets considerable influence from the Pacific Ocean, but also from higher elevation. Extending the season with a cold frame, greenhouse and row covers is key to a productive garden.
Average winter lows in Zone 4 range from 34°F (1°C) down to 28°F (–2°C),with extreme lows averaging 8 to 0°F (–13 to –18°C). The growing season is 150 to 200 days long, but because Zone 4 summers are temperate (highs average from the low 60s to the 70s), plants take more time to develop. If you’re growing vegetables, for example, add at least 50 percent to the days-to-harvest figure listed on the seed package, or start your garden from transplants.
USDA Climate Zones of the Klamath-Trinity
Most gardeners are familiar with the USDA zones listed in the adjacent map and chart, they account only for the minimum average annual temperature so they are used to rate a plant’s cold-hardiness. Using this system, most of the Mid Klamath falls into climate zones 8 & 9.
Microclimates
Microclimates are small pockets of climate variations that differ from the surrounding climate. By identifying and using microclimates you can grow fruit and veggies not normally recommended for your climate zone. Pay attention to the way the sun travels across your property throughout the season. Look for cold spots and hot spots. A maximum-minimum thermometer placed at different locations will tell you a lot about your microclimates. Here are a few other things to look for.
Slope - the Banana Belt Effect – Cold air moves like water, so in spring and fall a valley floor will usually be significantly colder than a slope. Some slopes are called banana belts, because they remain frost-free much longer than valley floors, which may be subjected to hard frosts, a common phenomenon in the Mid Klamath. Banana belts occur in areas with at least a 3 ½ % slope (150 feet/ mile) that is 100 to 200 feet higher than the nearest spot where frost can settle. These banana belts can be 8 – 15 degrees warmer on frosty nights. Utilize this if you are in a cold climate and are concerned about frost damage, make the best use of slopes when available.
Aspect - A south-facing slope is, of course, much warmer than a north-facing slope. Western slopes receive the hotter, more intense afternoon sunshine, while eastern slopes receive the less intense morning sun. A south facing wall is a good place to plant a tree that needs extra heat in order to ripen. If the wall has an overhang, it will also provide some frost protection. The influence of aspect can become dramatic in the winter when some north facing slopes and drainages may receive little or no sun; these areas often retain frost all day long on the shortest days, while adjacent areas with a different aspect may be warm and sunny.
Treeline, Ridgeline & Shade- The steep valleys and tall conifer forests of the Mid Klamath region create lots of shaded areas. Shade can be an asset in the long, hot days of summer, creating microclimates for crops that are less heat tolerant; and a liability in the winter, when shaded areas may never see the sun and retain ice and frost the entire day.
Thermal mass – Water and stone will absorb heat during the day and re-radiate it at night. A stone or brick wall can be an ideal place for ripening a late fruit crop. Translucent jugs of water placed in a greenhouse or around fruit trees will re-radiate heat at night. A small pond will serve as a heat sink in the summer and fall, and a cold sink in spring and winter. Watering before an anticipated frost will increase re-radiated heat – the wet soil will absorb more heat than dry soil during the day, and release more at night.
Wind – Strong wind can dehydrate plants, damage fruit and decrease air temperatures. Wind protection can be especially important in coastal or desert regions. The best windbreak is one that slows wind down rather than stopping it. A solid wall set perpendicular to prevailing winds will result in lots of turbulence on the downwind side. Hedges, vines, lattice fences and screens allow some wind to pass through without creating turbulence.