This month has the distinction of being the fastest-changing of any month here in Portland. That’s temperature-wise. The high temp drops 12 degrees from 70 on the first to 58 on Halloween. No other month sees such a rapid rise or fall. It’s not really part of our rainy season although in some years the rainy season really kicks in the 2nd part of the month.
September was a somewhat boring weather month this year. Temperatures were near or just slightly below normal and rain was below normal.
We’re seeing a few sprinkles or showers moving through the area this evening as a cold upper level trough drops south through the Pacific Northwest. The center of the low is just coming across the border into Washington at this hour. It’s moving quickly and by sunset tomorrow it’ll already be into Nevada. The result is a quick breakout to sunshine Saturday west of the Cascades as drier northeasterly flow moves in. We have a beautiful weekend on the way!
The weather pattern for this first week or so of October appears to be very mild with upper-level ridging remaining near the West Coast most of the next 10 days. Note the ECMWF ensemble 850mb temperature chart shows above average temperatures through the 17th.
Chief Meteorologist Mark Nelsen