2021 NW Heatwave Perspectives

The following constitute a brief retrospective of the yearly highest maximum temperatures observed in Washington and Oregon. The data are from the Global Historical Climatic Network (GHCN) at (https://www1.ncdc.noaa.gov/pub/data/ghcn/daily/by_station/).

The stations are selected for only those with observations records which are at least eighty percent complete since 1895. As of August 3, 2021, records for some stations had still not been validated through the remarkable heatwave event of June 28, 2021. Of those stations,

Temperatures above 110F have occurred numerous times in the records for both Washington and Oregon, though periods of three decades without such events also occurred in each state (Figures 1a and 2a).

The statewide all time highest maximum temperatures for the eighty percent complete stations were first set in 1898 near the beginning of records. ( Dotted red lines of Figures 1b and 2b).

The mean of all stations’ yearly highest maximum temperatures was highest for 2021, indicating that the area of extreme heat was large. ( solid black lines of Figures 1b and 2b).

For Washington, of the eighteen stations with observations through the June 28, 2021 event, nine of these eighteen set new all time maximum records in 2021, while nine others did not eclipse previous record highs.