Multnomah County (Portland)
September
Weather in Multnomah County, Oregon for September 2026
Your guide to Multnomah County weather in September - trends and predictions
In general, the average temperature in Multnomah County at the beginning of September is 28.1 °C. As the month progressed, temperatures tended to significantly cool down, reaching an average of 21.1 °C by the end of September.
The climate of Multnomah County in September is notably wet, with an average of 12 rainy days, and a total of 61.9 mm of precipitation.
New! Chat with our AI weatherman - it’s amazing and free.
Temperatures
Rain 🌧️
More
18
Dry days
12
Rainy days
0
Snow days
24°/13°
Temperatures
10 km/h
Avg max wind
63 %
Avg humidity
Multnomah County Weather September
Move between months or click on a day
Temperatures trend during September in Multnomah County
See the weather trend as well as the moving average line
September weather in Multnomah County day by day
Click on a date for more information
| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Fog | 28° /15° | 0.1 mm | 6 | |
| Sept. 2 |  Cloudy | 28° /15° | 0.1 mm | 7 | |
| Sept. 3 |  Patchy rain possible | 27° /16° | 0.8 mm | 6 | |
| Sept. 4 |  Overcast | 28° /13° | 0.7 mm | 6 | |
| Sept. 5 | Overcast | 32° /16° | 0 mm | 8 | |
| Sept. 6 |  Partly cloudy | 29° /16° | 0 mm | 7 | |
| Sept. 7 | Overcast | 25° /15° | 0 mm | 6 | |
| Sept. 8 | Overcast | 26° /15° | 5.2 mm | 6 | |
| Sept. 9 | Cloudy | 26° /13° | 10.2 mm | 6 | |
| Sept. 10 |  Sunny | 25° /14° | 0 mm | 6 | |
| Sept. 11 | Overcast | 20° /13° | 3.7 mm | 4 | |
| Sept. 12 | Cloudy | 21° /12° | 0.2 mm | 5 | |
| Sept. 13 | Overcast | 24° /11° | 0 mm | 6 | |
| Sept. 14 | Sunny | 25° /12° | 1.4 mm | 6 | |
| Sept. 15 | Sunny | 27° /11° | 0 mm | 7 | |
| Sept. 16 | Sunny | 29° /13° | 0 mm | 7 | |
| Sept. 17 | Overcast | 23° /13° | 4 mm | 6 | |
| Sept. 18 | Overcast | 22° /13° | 0 mm | 5 | |
| Sept. 19 | Overcast | 23° /13° | 0 mm | 6 | |
| Sept. 20 | Light rain shower | 22° /12° | 0.5 mm | 5 | |
| Sept. 21 | Partly cloudy | 23° /10° | 5.7 mm | 6 | |
| Sept. 22 | Sunny | 24° /11° | 0 mm | 6 | |
| Sept. 23 | Light rain shower | 26° /13° | 0.5 mm | 6 | |
| Sept. 24 | Sunny | 27° /14° | 1.4 mm | 7 | |
| Sept. 25 | Light rain shower | 19° /13° | 4.6 mm | 4 | |
| Sept. 26 | Light rain shower | 21° /11° | 3.5 mm | 5 | |
| Sept. 27 | Overcast | 22° /13° | 4.2 mm | 5 | |
| Sept. 28 | Patchy rain possible | 20° /11° | 0.1 mm | 5 | |
| Sept. 29 | Overcast | 18° /11° | 6.6 mm | 4 | |
| Sept. 30 | Partly cloudy | 21° /9° | 8.2 mm | 5 | |
| Next | |||||
Important Notice
Our weather forecast for Multnomah 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 Multnomah County forecast closer to your planned date for the most up-to-date weather information.
Change Month
Multnomah County in September - FAQ
What are the expected maximum and minimum temperatures in Multnomah County during September?
Enjoy moderate daytime temperatures of up to 24° and cooler nights around 13°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Multnomah County during September?
Moderate rainfall is anticipated in Multnomah County during September, with a total of 61.9 mm spread over approximately 12 days. Considering plans for rainy days is advisable.
What are the typical wind conditions in Multnomah County during September?
The average wind speed in Multnomah County during September is 10 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Multnomah County
Explore the daily rainfall trends and prepare for Multnomah Countys September weather 💧
Typically, Multnomah County has 12 rainy days in September with a total of 61.9 mm of rainfall.
UV exposure in Multnomah County during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
Top locations in Multnomah County
Select a location for an accurate weather forecast
More Locations Quick links
More Multnomah County weather pages
You are here
Where is Multnomah County?Get accurate weather forecasts for Multnomah County, located at latitude 45.523 and longitude -122.676. Stay updated with localized weather information tailored for Multnomah County.
Found a mistake?
We appreciate your attention to details. Tell us here.