Multnomah County (Portland)
September
Weather in Multnomah County, Oregon for September 2025
Your guide to Multnomah County weather in September - trends and predictions
Until now, September 2025 in Multnomah County is slightly cooler than the historical average by -1.5 °F.
The forecast for the next days in Multnomah County predicts a temperature of 21.5 °F, which is cooler than the historical average.
In general, the average temperature in Multnomah County at the beginning of September is 28.1 °F. As the month progressed, temperatures tended to significantly cool down, reaching an average of 18 °F by the end of September.
Multnomah County experiences moderate rainfall in September, with an average of 8 rainy days and a total precipitation of 37 mm.
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Temperatures
Rain 🌧️
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22
Dry days
8
Rainy days
0
Snow days
24°/13°
Temperatures
11 km/h
Avg max wind
62 %
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 |  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 | Sunny | 27° /16° | 0 mm | 1.3 | |
| Sept. 18 | Sunny | 24° /14° | 0 mm | 1.2 | |
| Sept. 19 | Sunny | 27° /13° | 0 mm | 1.2 | |
| Sept. 20 | Patchy rain possible | 25° /13° | 0.5 mm | 1.2 | |
| Sept. 21 |  Moderate rain | 23° /13° | 6.6 mm | 1.1 | |
| Sept. 22 | Sunny | 25° /11° | 0 mm | 0 | |
| Sept. 23 | Partly cloudy | 24° /13° | 0 mm | 5 | |
| Sept. 24 | Patchy rain possible | 15° /13° | 0.6 mm | 3 | |
| Sept. 25 | Patchy rain possible | 17° /12° | 3.9 mm | 3 | |
| Sept. 26 | Patchy rain possible | 17° /12° | 2.1 mm | 3 | |
| Sept. 27 | Patchy rain possible | 20° /12° | 0.2 mm | 4 | |
| Sept. 28 | Patchy rain possible | 20° /11° | 0.1 mm | 3 | |
| Sept. 29 | Patchy rain possible | 18° /11° | 0.3 mm | 3 | |
| Sept. 30 | Patchy rain possible | 19° /11° | 0.1 mm | 3 | |
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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?
In September, Multnomah County can expect light to moderate rainfall, totaling 37 mm across approximately 8 days. Occasional showers are possible, and planning ahead for them could be helpful.
What are the typical wind conditions in Multnomah County during September?
The average wind speed in Multnomah County during September is 11 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 💧
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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