California Geography, Climate & Nature

California covers 163,696 square miles on the Pacific coast of North America, bordered by Oregon to the north, Nevada and Arizona to the east -- a straight line through the middle of Lake Tahoe and another to the Colorado River -- and the Mexican state of Baja California to the south. Geologists divide it into eleven provinces from north to south -- the Klamath Mountains, the Cascade Range, the Modoc Plateau, the Basin and Range, the Coast Ranges, the Central Valley, the Sierra Nevada, the Transverse Ranges, the Mojave Desert, the Peninsular Ranges and the Colorado Desert -- and the visitor meets four of them: a coast that runs from the fog-bound redwood rainforest of the north-west through the Bay and Big Sur to the beaches of the south; the Central Valley, about 11 per cent of the state's land, walled by the Coast Ranges and the Sierra and growing more than half the country's fruit, vegetables and nuts on seven million irrigated acres; the Sierra Nevada, a granite range whose western slope holds the giant sequoia groves, Yosemite Valley, three national parks and Lake Tahoe, the largest alpine lake in North America at 6,225 feet, and whose crest at Mount Whitney is the highest point in the contiguous states at 14,505 feet; and the deserts east and south of the mountains, the Mojave with its endemic Joshua trees and the Colorado Desert, where Death Valley's Badwater Basin lies 282 feet below sea level, the lowest point in North America, within a hundred miles of Whitney.

The state holds the tallest trees on earth, the coast redwoods, the most massive, the giant sequoias, and the oldest, the bristlecone pines of the White-Inyo Range east of the Sierra. Two-thirds of the nation's earthquake risk lies here along the San Andreas and its relatives; the volcanic north around Lassen still steams; and the Sacramento–San Joaquin Delta, where the two great valley rivers meet, supplies drinking water to nearly 23 million people through pumps and canals that run almost the length of the state.

Los Angeles, with 3.87 million people in the city and the second-largest metropolis in the country around it, and the San Francisco Bay Area are the nation's second and fifth most populous combined areas; San Diego, over 1.4 million, sits on the busiest land border crossing outside Asia; Sacramento, the capital since 1854, lies where the American River meets the Sacramento. Highway 1 runs 656 miles of the coast, the longest state route in California.

California's climate runs from hot desert to alpine tundra with latitude, elevation and distance from the sea, but the coast, the Sierra foothills and much of the Central Valley share a Mediterranean pattern: warm dry summers and cool wet winters, with the ocean moderating both -- warmer winters and much cooler summers on the shore. The difference between coast and interior in summer is about 20 degrees Fahrenheit: San Francisco's average July and August high is in the low to mid-sixties while Walnut Creek, 20 miles inland, reaches 84, and the Central Valley routinely passes 100. Los Angeles averages 29/18 °C in August and 20/8 in January with 377 millimetres of rain a year; San Francisco 20/12 and 14/8 with 538; San Diego gets 262 millimetres; the redwood coast over 100 inches. The south-east is hot desert like the Sahara: Death Valley commonly passes 120 °F in summer, recorded the highest reliable temperature on earth, 134 °F, on 10 July 1913, and averages 101.8 °F across the day and night in July. The Sierra, the Cascades and the Klamaths have mountain climates, and the resorts at Lake Tahoe, Mammoth Lakes and Mount Shasta routinely receive over ten feet of snow a season.

Two local phenomena shape a visit. June Gloom is the marine layer that greys the Southern California coast in late spring and early summer -- May Gray, No-Sky July and Fogust in local usage. The Santa Ana winds are the hot, dry, high winds that pour from the deserts toward the southern coast in autumn and spring, bringing the hottest and driest days of the year and critical fire weather; their northern counterpart is the Diablo. The state is warming and drying overall with increasing weather whiplash: the 2011–2017 drought was the worst on record, and the Canadian advisory names California among the earthquake-prone states and heat from June to September as a hazard.

Best Destinations by Month has the practical reading.

California holds the tallest trees on earth, the coast redwoods that reach 381 feet and 2,000 years on the fog-fed north coast; the most massive, the giant sequoias of the Sierra's western slope, the largest living organisms on the planet at up to 3,266 years old, with the General Sherman tree the largest by volume; and the oldest, the Great Basin bristlecone pines of the White-Inyo Range, one of which has passed 4,800 years, the oldest known individual of any species. Its habitats run from temperate rainforest and chaparral to alpine granite, the Central Valley's oaks and cottonwoods, the Mojave's Joshua trees and the Colorado Desert's cactus, mesquite and paloverde, and the California poppy is the state flower. The bird list stands at 687 species; the California quail is the state bird; and the Colorado River basin once held 49 native fish, 42 of them endemic.

The protected estate began with Lincoln's Yosemite Grant of 1864 and the national park of 1890, a World Heritage Site since 1984 with 95 per cent of it wilderness, and now includes Sequoia and Kings Canyon National Parks, Death Valley -- the largest park in the contiguous states, 93 per cent wilderness -- Joshua Tree, larger than Rhode Island across two deserts, Lassen's volcanic country, Pinnacles, the Channel Islands with their endemic fox, Point Reyes with its reintroduced tule elk, and the four Redwood parks holding 45 per cent of all remaining old-growth redwood, plus Anza-Borrego, the largest state park in California, and 26 wilderness areas in the Sierra alone. The condor, down to 27 birds in 1987, flies again from Pinnacles and the coastal mountains; the grizzly on the flag is gone.

The threats are fire, which now kills even sequoias, drought, the air pollution of the San Joaquin Valley, and the dams and diversions that drove four native fish of the Colorado River extinct. No fuller species inventory was consulted beyond the sources named in the data file.

The animals a visitor can plan on are the black bears of Yosemite and the Sierra, which is why the food lockers exist; mule deer, coyotes and the occasional bobcat almost anywhere; sea lions on the piers and sea otters in the kelp off Monterey and Big Sur; elephant seals at Piedras Blancas near San Simeon and Año Nuevo; gray whales passing the headlands on their migration in winter and spring; tule elk at Point Reyes and Roosevelt elk among the redwoods; the island fox on the Channel Islands; and, with luck and binoculars, a California condor over Pinnacles or the Big Sur coast. Mountain lions are present everywhere and seen almost never.

The practical zoology is the advisories' and the parks': rabies may be present in wildlife including bats; bears want your food, not you, and every campground has the rules; rattlesnakes are common; and the deserts and high country punish the unprepared with heat, altitude and exposure long before any animal does.