Portland Weather in September
United States · Oceanic climate · Data averaged from 2020-01-01 to 2024-12-31 (5 years)
September in Portland sees average temperatures ranging from a low of 12.9°C (55.2°F) to a high of 25.1°C (77.2°F), with a mean of 18.3°C (64.9°F). Compared to the annual average of 11.9°C (53.4°F), this month is 6.4°C warmer than the yearly norm. Precipitation averages 65.2mm, making it approximately 54.0mm drier than the monthly average of 120.0mm. The city receives an average of 10.0 hours of sunshine per day during September, with relative humidity averaging 66.4%. Wind speeds reach an average maximum of 15.3 km/h. For travelers, this month offers a temperature experience in Portland, with drier-than-average conditions compared to the rest of the year.
Portland's climate is similar to Seattle but with slightly warmer summers and cooler winters. I visited during the famous rose festival in June and found the weather ideal. The data shows that the best time to visit is June to September, when the rainfall is minimal and the city's famous outdoor culture thrives. The winter months are grey and wet but the city's coffee shop culture makes it cozy.
September vs Adjacent Months
| Metric | August | September | October |
|---|---|---|---|
| Mean Temp | 21.5°C (70.7°F) | 18.3°C (64.9°F) | 12.7°C (54.9°F) |
| Rainfall | 13.2mm | 65.2mm | 111.8mm |
| Sunshine | 11.9 hrs | 10.0 hrs | 7.0 hrs |
| Humidity | 58.9% | 66.4% | 78.7% |
| Wind | 15.9 km/h | 15.3 km/h | 15.6 km/h |
| Rainy Days | 4.8 | 9.4 | 14.4 |
Seasonal Context
September falls in Autumn in the Northern Hemisphere. Autumn sees temperatures gradually cooling from summer highs. For travelers visiting Portland in September, the data indicates favorable conditions based on the combination of temperature, precipitation, and daylight hours.
Frequently Asked Questions
What is the average temperature in Portland in September?
The average temperature in Portland during September ranges from 12.9°C (55.2°F) to 25.1°C (77.2°F), with a mean of 18.3°C (64.9°F).
How much does it rain in Portland in September?
Portland receives an average of 65.2mm of precipitation in September, spread across approximately 9.4 rainy days.
What should I pack for Portland in September?
Based on September weather data, pack layers including light jackets and t-shirts, plus an umbrella.
Is September a good time to visit Portland?
September is a good time to visit Portland, with comfortable temperatures and manageable rainfall.
Other Months for Portland
Cities with Similar September Climate (Oceanic)
Data Source: Open-Meteo historical archive (2020-01-01 to 2024-12-31). Daily measurements aggregated into monthly climate normals. Coordinates: 45.52°, -122.68°. Timezone: America/Los_Angeles. Last updated: 2026-07-30.