September was cool and dry

Remember September? It was cooler than normal, the sun blocked by California and Oregon’s wildfire smoke. Maximum temperatures averaged 3.8 degrees below the century’s 71.4 monthly average high from the 12th through the end of the month.

Recall that warm was the norm the first 10 days. Temperatures topped 80 degrees three of four days starting the 7th. Half of those days saw highs above 75 degrees. That changed abruptly on the 12th, when the high was 59 degrees. Only two days rose above 72 degrees the rest of the month, while on 13 days it stayed in the 60s and twice, on the 12th and 26th, the temperature did not reach 60 degrees.

Average temperatures were above the 20 year averages, fueled by the month’s warm start. The average low of 50 degrees was a degree higher; the average high of 71 degrees was three degrees higher, and the 60.2 daily average was two degrees higher.

It only rained 1.1”, with no rain the first 13 days. Most of that, 0.97” fell Sept. 23-26. Sprinkles three times between Sept. 14-18 was the only other precipitation.

Last year’s 5.2” of rain was the most since 2000.

This year’s rain was half the September average of 1.9” this century. Five of the wettest Septembers have been since 2010. There has been at least 2” of rain eight years and over 3” three times.

Measurements and data are at Washington State University’s Mount Vernon weather station on Memorial Highway.