The Western United States freeze of 2007 was a weather event affecting California, Oregon, and Washington from January 12 to January 18, 2007. An Arctic low pressure system dipped extremely far west, resulting in record cold temperatures in the western states, damaged citrus crops in California, and extremely unusual snow accumulation occurring in areas of Southern California.
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An unusually mild winter across many parts of the Southwest and Pacific Northwest paved the way for an extreme blast of Arctic air that dipped extremely far south causing Arctic snow conditions in the Pacific Northwest and unusually frigid temperatures in Southern California and the San Joaquin Valley. December brought extremely dry conditions for Southern California as well as unusually warm weather, with relatively little cloud cover in the area. Los Angeles averaged well over 3 degrees above average for the month of December. In the Pacific Northwest, the area was continually blasted with unusually large rain storms causing flooding in much of Washington and Oregon. Temperatures began to drop below average in the San Joaquin Valley beginning January 11 and January 12 in Southern California. The first freeze occurred in the San Joaquin Valley around midnight on January 13. During this time, the middle of the nation was being affected by a severe ice storm system caused by the tail end of the same arctic air afflicting the west.
The invasion of cold air ranged from January 13 to January 18, 2007 and affected several areas of California, Oregon, and Washington in different ways.
Areas that rarely experience snow in Southern California received a rare glimpse of it during this cold spell. January 17 brought snow to areas of Malibu and West Los Angeles. The snow level dropped close to sea level during this cold snap, however no precipitation fell during January 14, January 15, or January 16 in the area when temperatures were at their coldest. Records were set across Southern California for temperatures as well. January 14, 2007 saw a low of 36°F (2°C) in downtown Los Angeles, a record for the day.[1] San Diego bottomed out at 36°F and 35°F (2°C) on consecutive mornings. Lancaster, a city set in the high desert of Los Angeles County, reached just 3°F (-16°C).[2] Many sections of the Grapevine freeway were closed due to snow, and several accidents occurred as a result of black ice.
Other consequences of this cold snap in Southern California were dying palm trees and other tropical plants that have thrived here.
The San Joaquin Valley is the largest citrus producing region in the United States, and the production of these fruits was adversely affected by this weather system. Cold-sensitive plants that grow in this area such as oranges, lemons, avocados, and flowers were greatly damaged due to the cold because they cannot tolerate a hard freeze. Temperatures in Los Banos, California dipped to 21°F (-6°C) on both January 14 and January 15. An estimated 75% of the nation's citrus crop has been destroyed by the cold weather with damages to some other crops such as strawberries and avocados and even fresh-cut flowers. The total damage in the area is estimated at around $1 billion dollars. Governor Arnold Schwarzenegger requested a federal disaster aid.[3][4][4]
These areas are much more prepared for cold temperatures, since they frequently receive them. However, Seattle, Washington dipped to 17 °F (-8.3 °C) on January 14,[5] and during this storm on the 16th and 17th, snow was recorded in record amounts in both Washington and Oregon with some areas receiving upwards of 12" (30 cm) of snow in the valleys, and 50" (1.3 m) in the mountain areas over the 2 day period. This benefited the local ski resorts in the Cascade Mountains and Sierra Nevada Mountains.