Not much May rain

The rain this weekend, 0.22”, was a tease and cannot make up for the paltry 0.87” of rain in May. Last month matched May 2019’s total. This is the fourth year since 2015 that less than 1” of rain fell. The 0.35” in 2018 made that May the century’s driest.

The 0.33” of rain May 6-7 was matched May 23-24. The two rain events were 76% of the month’s precipitation. In the 16 days between, it only rained three times, all below 0.05”. The last week brought 0.12” May 27-28.

May was a dry month in a dry year, with 12.45” of precipitation through five months. The century average for Jan-May, 2000-2021 is 15.15”, 3” more rain, 19% more. May’s century average is 2.24”, 61% more. February was the only month with precipitation above its monthly century average.

Five years since 2000 there has been less than one inch of May rain. Three years more than four inches have fallen. Eleven years there has been two or more inches of rain. Except for the years since 2015, there is no pattern to rainfall quantities this century for the 19 years of data.

The average daily high temperature of 63.6 F was just below the century average, while the 53.7 F daily average low temperature was one degree lower than the century average, brought down by morning lows of 43.6 F, 2.6 F below the century average.

Starting May 14, the high went above 70 F three days in a row, but that was an anomaly and followed by three days of highs not reaching 60 F. The month’s high temperature was 75.7 F on the 31st.

Six mornings, the last on the 29th, lows were below 40.0 F.

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