What will Mother Nature throw at the Willamette Valley this fall?

PORTLAND, Ore. (KOIN) — As the calendar inches towards autumn, the Pacific Northwest prepares to embrace a new chapter of weather. The scorching temperatures of summer give way to the cooler, more colorful tones of fall. The air turns crisp as frost arrives, and our streets turn rainy as more storms develop.

What is Normal Fall Weather?

The fall season officially starts on the fall equinox (September 22) and goes to the winter solstice (December 21). Normally, daytime highs tend to cool away from a comfortable zone in the 60s and 70s, to true sweater and puffy jacket weather in the 50s and 40s by November and December.

The rainy season usually picks back up in October. As more and stronger storms arrive with an active jet stream, average monthly rainfall increasing quickly in Portland throughout the coming months.

Thankfully, chances for snowfall in Portland are low before the month of December. Chilly temperatures set in during the last two month of the year. The average first freeze usually occurs in November and overnight lows drop to the mid 30s in December.

NOAA’s Climate Prediction Center Fall Outlook 2023

The Climate Prediction Center relies on historical climate data and sophisticated weather modeling to provide an extended weather outlook across parts of the year. This year, the 2023 fall outlook suggests that there is a higher likelihood of temperatures during the months of September, October, and November of being warmer-than-normal across the Pacific Northwest and southern United states. In terms of rainfall, the outlook suggests a higher likelihood for drier-than-normal conditions for the Pacific Northwest, and wetter-than-normal conditions for the southern coastal states.

The for Pacific Northwest, this could indicate longer periods of mild and drier weather in the months to come, compared to typical crisp, cool, and rainy fall pattern we are used to.

It is important to remember the climate outlook differs from a full, detailed weather forecast. This outlook spans months ahead of time when the weather is truly unpredictable. Even though the outlook is hinting at and warmer and drier fall, impactful weather will still arrive at times across the coming months, bringing soggy, windy, and chilly moments to the Portland metro area.

The best thing to stay informed about the weather is to keep watch of the forecast with the KOIN 6 Weather team as we head into the cooler and stormier months of the year.