From a temperature standpoint, Autumn is off to an unusually mild start across the Northwest.
The federal government’s Western Regional Climate Center generates charts of climate anomalies. They show average daily temps running two to six degrees above normal for the past month in nearly all of Oregon, Washington, Idaho and Montana.
Washington State Climatologist Nick Bond said a lingering patch of warm water in the eastern Pacific is contributing to the balmy weather.
“Especially at night, it has been really balmy,” he said. “That air has been coming off that warm water and just been warmed and moistened as a consequence.”
Another important reason for the mild start to fall is a persistent trough of low pressure west of British Columbia. University of Washington weather blogger Cliff Mass wrote this changed the prevailing winds over us to southerlies “that blow in warmer than normal air.”