Multnomah County (Portland)
September
Weather in Multnomah County, Oregon for September 2026
Your guide to Multnomah County weather in September - trends and predictions
Until now, September 2026 in Multnomah County is cooler than usual, with temperatures averaging 21.3 °F, this is 4 °F below the typical seasonal average.
The forecast for the next days in Multnomah County predicts temperatures to be around 24 °F, close to the historical average.
In general, the average temperature in Multnomah County at the beginning of September is 26.3 °F. As the month progressed, temperatures tended to noticeably cool down, reaching an average of 23.4 °F by the end of September.
With an average of 5 rainy days, Multnomah County experiences minimal rainfall in September.
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Temperatures
Rain 🌧️
More
25
Dry days
5
Rainy days
0
Snow days
24°/13°
Temperatures
10 km/h
Avg max wind
63 %
Avg humidity
Multnomah County Weather September
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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
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Overcast | 27° /14° | 0.1 mm | 5 | |
| Sept. 2 |  Cloudy | 26° /14° | 13.1 mm | 6 | |
| Sept. 3 |  Patchy rain possible | 25° /15° | 3.6 mm | 5 | |
| Sept. 4 | Overcast | 25° /13° | 6.4 mm | 5 | |
| Sept. 5 |  Sunny | 30° /14° | 0 mm | 7 | |
| Sept. 6 |  Partly cloudy | 26° /15° | 10.1 mm | 6 | |
| Sept. 7 | Overcast | 25° /14° | 0.1 mm | 5 | |
| Sept. 8 | Sunny | 27° /14° | 3.9 mm | 6 | |
| Sept. 9 | Cloudy | 27° /13° | 7.6 mm | 6 | |
| Sept. 10 | Overcast | 25° /13° | 0 mm | 6 | |
| Sept. 11 | Overcast | 20° /12° | 2.8 mm | 4 | |
| Sept. 12 | Overcast | 21° /12° | 1.2 mm | 4 | |
| Sept. 13 | Overcast | 22° /11° | 0.4 mm | 5 | |
| Sept. 14 | Sunny | 24° /11° | 1.2 mm | 6 | |
| Sept. 15 | Sunny | 25° /11° | 0.2 mm | 5 | |
| Sept. 16 | Sunny | 29° /13° | 0 mm | 7 | |
| Sept. 17 | Sunny | 24° /13° | 3 mm | 6 | |
| Sept. 18 | Sunny | 25° /13° | 0 mm | 4.9 | |
| Sept. 19 | Partly cloudy | 26° /12° | 0 mm | 4.9 | |
| Sept. 20 | Sunny | 27° /12° | 0 mm | 4.9 | |
| Sept. 21 | Sunny | 21° /12° | 0 mm | 4.9 | |
| Sept. 22 | Sunny | 23° /10° | 0 mm | 6 | |
| Sept. 23 | Sunny | 28° /12° | 0 mm | 7 | |
| Sept. 24 | Sunny | 31° /16° | 0 mm | 8 | |
| Sept. 25 | Overcast | 29° /18° | 0 mm | 7 | |
| Sept. 26 | Patchy rain possible | 18° /11° | 0.5 mm | 4 | |
| Sept. 27 | Overcast | 18° /10° | 0 mm | 5 | |
| Sept. 28 | Sunny | 22° /7° | 0 mm | 6 | |
| Sept. 29 | Sunny | 23° /8° | 0 mm | 6 | |
| Sept. 30 | Overcast | 23° /10° | 0 mm | 6 | |
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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.
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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 5 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 5 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 ☀️
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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.
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