Country Guide

California

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California enjoys a very distinctive climate of the Mediterranean type and this climatic region is almost coincident with the state boundary. The northern coast of California has a climate similar to the coastal districts of the northwest but there is a gradual increase in summer temperature southwards and a decrease of rainfall until the summers become completely dry in central and southern California.

In the southeast of the state precipitation decreases until conditions become similar to those of the desert regions of neighbouring Arizona and northern Mexico. Most of California enjoys mild and moderately wet winters and warm to hot and very dry summers.

There are some large mountain regions within the state: the coast ranges and the Sierra Nevada, which rise to over 3,700 m/12,000 ft. These mountains have a heavy precipitation and, at higher levels, much of this is snow so there are many opportunities for winter sports within a state that is often associated with sun, sea and warmth.

The tables for San Francisco, Los Angeles and San Diego are representative of the coastal region. San Francisco is unusual in having cool to mild summers. This is a very local feature caused by the frequent sea fog which sweeps into the bay through the Golden Gate gap in the coast range.

Elsewhere this sea fog rarely affects the land but the cool waters of the California current help to maintain much lower summer temperatures on the coast than inland. In the Great Valley of California and in the desert areas in the southeast, summer temperatures are much higher. Frost and snow are very rare occurrences on the coast but occur more frequently inland in winter.

The table for Death Valley shows the extremely high temperatures here in summer. This place has not only experienced the highest temperatures in the United States but some of the highest recorded anywhere in the world.

The winter precipitation of California is caused but the same sequence of cyclonic depressions as bring rain to the states of the northwest. In summer such disturbances are pushed farther north by the almost permanent presence of the North Pacific subtropical anticyclone which brings the calm, settled and sunny weather.

This anticyclone is also responsible, however, for the most unpleasant and dangerous weather phenomenon which particularly affects the great urban area of Los Angeles: urban smog. This is a combination of fog and pollution from automobiles and industry. The pollution is trapped beneath a layer of warm air which overlies the coast; the light winds are unable to disperse it beyond the encircling hills and mountains.

Apart from this particular hazard most of California has a very agreeable and healthy climate throughout the year: sunny and dry with only short periods of relatively cold weather in winter. The visitor should obviously avoid going to such 'hot spots' as Death Valley without taking sensible precautions, or ignoring the fact that very heavy snowstorms can occur in the mountains of California.

California is one of the sunniest states in the country. Sunshine hours a day average from seven to eight in winter to as many as twelve to fourteen in summer in the driest regions inland. On the coast they are rather less: from six to seven in winter and nine to ten in summer. The reduction in summer sunshine on the coast is because of sea fog.

Click on the links below for a detailed look at the United States regions:

USA
Northeastern States (New England)
southern Atlantic States
Northern Interior (Midwest)
Southern Interior and Gulf States
States of the Rocky Mountains Region
States of the Pacific Northwest
California
Alaska
Hawaii