Seattle weather in September
Long-run climate averages for Seattle, WA in September, plus what the forecast models say for the days ahead.
In September, Seattle averages 69°F by day and 55°F at night. The wettest month is usually December.
September in Seattle averages a daytime high of 69°F and an overnight low of 55°F, which reads as mild for this part of the world. Across the whole year Seattle sees roughly 43 inches of precipitation.
Climate averages tell you what to pack. They do not tell you what next Tuesday looks like — for that, see the live Seattle forecast with every model compared and how much they currently agree.
Seattle weather by month
what to expect in Seattle through the yearHere is Seattle's typical weather in each month: the average daytime high and overnight low in °F, how each month feels, and the wettest month marked. Use it to plan any trip to Seattle by season.