Excessive Heat in Modoc County, California

Alturas (AAT) was the only station from this zone that reported observations. On 06/26/21, the low temperature was 48 degrees and the high temperature was 96 degrees. On 06/27/21, the low temperature was 56 degrees and the high temperature was 100 degrees. On 06/28/21, the low temperature was 59 degrees and the high temperature was 105 degrees. On 06/29/21, the low temperature was 53 degrees and the high temperature was 103 degrees. On 06/30/21, the low temperature was 53 degrees and the high temperature was 98 degrees. On 06/28/21, the high temperature reading of 105 in Alturas set a high temperature record for the month of June. The old record was 102 degrees on 06/25/1961.

A historic heat wave affected the Pacific Northwest during this interval. It was caused by a strong upper level ridge that created dry and stable conditions over the area with strong subsidence. Many daily, monthly, and all-time high temperature records were set over northern California.