Weather in Seattle for the month
The full September calendar: model forecast through September 30, then the long-term climate normal.
🔮 What September will be like
📅 September calendar2-week forecast →
🌅 September astronomy
📒 Weather diary in Seattle
Ready-made observation table for September: past days are already filled in with weather-station data — for school and beyond. Open the diary →
✉️ Weather forecast by email
Get the forecast for this city by email — every day at 17:00 Moscow time.
FAQ about weather in Seattle ❓
What will the weather be like in September in Seattle?
The forecast part of September: +14°…+20° by day, no prolonged rain.
When are the best days of September?
The forecast points to 30 September: +20°. Models don’t see beyond two weeks — check back, the page updates daily.
How accurate is a monthly forecast?
Honestly: models are reliable up to ~14 days. So through September 30 we show the model forecast, and beyond that — each day’s climate normal from long-term observations (ERA5). It is a statistical expectation, not a guarantee.
Weather in Seattle — in detail
Weather forecast in Seattle for the month: from +10° to +20° day and night. Warmest day — Wednesday, September 30 (up to +20°). Coolest — Sunday, September 27 (+10°). No significant precipitation. Trend: with no sharp changes. See also the forecast for 2 weeks and the weather archive.
To quickly check the weather in Seattle anytime, add the city to favorites — and get a daily forecast by email at 17:00 (Moscow time). Note: the forecast may be refined as new data arrives. Data: OpenWeather, Open-Meteo, met.no.