The summer of 2021 was the Pacific Northwest’s hottest in a millennium

A two-week-long heat wave in the Pacific Northwest in 2021 helped make that summer a record breaker for the region (SN: 7/7/21). Now, tree ring data from the area’s forests reveal that the summer of 2021 was also the region’s hottest of the last millennium.

The average temperature for that year’s summer not only shattered the previous record, set in 2015, by 0.4 degrees Celsius. It was also unprecedented since the year 950, researchers reported February 17 in npj Climate and Atmospheric Science.