easeweather.com
Units
°C
°F
Snohomish County
Forecast Today Tomorrow
more
Washington United States

Weather in Snohomish County for September 2025

Your guide to Snohomish County weather in September - trends and predictions

    Temperatures

  • In general, the average temperature in Snohomish County at the beginning of September is 24.6 °F. As the month progressed, temperatures tended to significantly cool down, reaching an average of 15.4 °F by the end of September.

  • Rain 🌧️

  • Snohomish County experiences moderate rainfall in September, with an average of 6 rainy days and a total precipitation of 49.4 mm.

  • More

  • New! Chat with our AI weatherman - it’s amazing and free.

Average dry days
24
Dry days
Average rainy days
6
Rainy days
Average snowy days
0
Snow days
Average temperatures
19°/11°
Temperatures
Average wind speed
9 km/h
Avg max wind
Average humidity
82 %
Avg humidity

Snohomish County Weather September

Move between months or click on a day
Select a date

You can click on date

Access Snohomish County weather forecasts with a simple click. Select any date for comprehensive insights on temperature, rainfall, and wind conditions.
Got it

Temperatures trend during September in Snohomish County

See the weather trend as well as the moving average line

September weather day by day

Click on a date for more information
Date Weather Temperatures Rain UV More
Sept. 1 Partly cloudy
Partly cloudy
26° /14° 0 mm 7
Sept. 2 Fog
Fog
24° /12° 0 mm 5
Sept. 3 Patchy rain possible
Patchy rain possible
22° /12° 0 mm 5
Sept. 4 Fog
Fog
23° /11° 0 mm 5
Sept. 5 Sunny
Sunny
27° /14° 0 mm 7
Sept. 6 Sunny
Sunny
26° /14° 0 mm 7
Sept. 7 Partly cloudy
Partly cloudy
24° /14° 0 mm 6
Sept. 8 Sunny
Sunny
27° /13° 0 mm 7
Sept. 9 Fog
Fog
22° /11° 0 mm 5
Sept. 10 Patchy rain possible
Patchy rain possible
21° /10° 0.1 mm 5
Sept. 11 Light rain
Light rain
12° /9° 4 mm 3
Sept. 12 Fog
Fog
18° /9° 0.1 mm 4
Sept. 13 Mist
Mist
20° /10° 1.2 mm 5
Sept. 14 Light rain shower
Light rain shower
18° /12° 4.8 mm 4
Sept. 15 Fog
Fog
17° /10° 0.1 mm 4
Sept. 16 Mist
Mist
20° /8° 0 mm 5
Sept. 17 Fog
Fog
14° /10° 0 mm 3
Sept. 18 Fog
Fog
14° /12° 0 mm 3
Sept. 19 Mist
Mist
14° /10° 0 mm 3
Sept. 20 Mist
Mist
15° /9° 0 mm 4
Sept. 21 Mist
Mist
18° /7° 0 mm 4
Sept. 22 Overcast
Overcast
18° /11° 0 mm 4
Sept. 23 Mist
Mist
19° /15° 0 mm 4
Sept. 24 Mist
Mist
21° /12° 0 mm 5
Sept. 25 Moderate or heavy rain with thunder
Moderate or heavy rain with thunder
16° /12° 20.8 mm 4
Sept. 26 Moderate rain at times
Moderate rain at times
15° /10° 14 mm 4
Sept. 27 Mist
Mist
16° /11° 4.2 mm 4
Sept. 28 Mist
Mist
13° /9° 0 mm 3
Sept. 29 Mist
Mist
13° /5° 0 mm 3
Sept. 30 Cloudy
Cloudy
14° /6° 0 mm 3
Next
Important Notice
Our weather forecast for Snohomish County in September is based on the analysis of historical data rather than real-time forecast models. While this provides a general overview, weather conditions can change. We recommend that you check the Snohomish County forecast closer to your planned date for the most up-to-date weather information.

Snohomish County in September - FAQ

What are the expected maximum and minimum temperatures in Snohomish County during September?
Enjoy moderate daytime temperatures of up to 19° and cooler nights around 11°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Snohomish County during September?
In September, Snohomish County can expect light to moderate rainfall, totaling 49.4 mm across approximately 6 days. Occasional showers are possible, and planning ahead for them could be helpful.
What are the typical wind conditions in Snohomish County during September?
The average wind speed in Snohomish County during September is 9 km/h, suggesting breezy to windy conditions, depending on your activities.

September rainfall patterns in Snohomish County

Explore the daily rainfall trends and prepare for Snohomish Countys September weather 💧

UV exposure in Snohomish County during September

Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
Top locations in Snohomish County
Select a location for an accurate weather forecast
More Locations

Quick links

Location coordinates Where is Snohomish County?

Get accurate weather forecasts for Snohomish County, located at latitude 47.979 and longitude -122.202. Stay updated with localized weather information tailored for Snohomish County.

Found a mistake?
We appreciate your attention to details. Tell us here.