Weather tracker: why is it so cold in California at the moment?

Precipitation has made the western US very cold and wet, with one ski lodge declaring this the snowiest season on record

Throughout the past several months there has been a recurring theme in weather news about how wet and unsettled western parts of the US have been, particularly for the normally sunny state of California. This has been due to frequent atmospheric rivers funnelling into western North America, and a recent analysis undertaken by the Scripps Institution of Oceanography found that over the course of this water year (1 October 2022 to 30 September 2023), a total of 31 atmospheric river events have affected the west coast of the USA so far.

This constant barrage of precipitation to the western US has meant that March in particular has seen precipitation anomalies far above normal, with widely at least two to three times more than usual. In addition, it has been exceptionally cold, with average temperatures for March widely at least 2-3C below normal, but with many places also having seen temperatures more than 5C below normal. Because of this, mountainous regions have seen precipitation falling mostly as snow throughout the month, this very heavy and frequent and has brought snow accumulations enough to bury an entire ski lodge in Rimforest, California. Mammoth Mountain ski resort has declared this the snowiest season on record with snow totals reaching 17.6m at their main lodge and a staggering 22.1m at the summit of the mountain peak. Cold and wet conditions are still expected to linger at least through the next week.