Climate averages 1991–2020
Portland weather
in August.
A warm, very dry month: the warmest and the 2nd driest of the year. Meets the pleasant-weather rule
Long-term climate patterns, not a forecast for a particular trip.
August is a warm month in Portland: daytime highs average 27.6°C and nights cool to about 14.6°C. By daytime temperature it is the warmest month of the year.
Expect about 14 mm of rain on roughly 3 days, which makes August a very dry month (the 2nd driest of the 12 months). Daylight, from sunrise to sunset, lasts about 14 h 07 min on an average August day.
The nearest other city in this atlas is Beaverton (11 km away). In August its highs average 27.1°C, about as warm as Portland, with 14 mm of rain.
Among the 498 cities listed in the United States, Portland ranks joint 344th of 498 for the warmest August highs and joint 128th of 498 for the driest August (rainfall, lowest first). The mean August high of those 498 cities is 29.9°C; Portland is 2.3°C cooler than that mean.
From August to September, average highs fall by 3.4°C to 24.1°C, and monthly rainfall rises from 14 mm to 42 mm.
The annual picture
August in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Portland climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 8.4°C1.7°C | 1.7°C | 167 | 17.3 | 9.19 h |
| February | 10.1°C2.0°C | 2.0°C | 130 | 15.0 | 10.310 h |
| March | 12.4°C3.4°C | 3.4°C | 145 | 17.5 | 11.912 h |
| April | 14.9°C5.4°C | 5.4°C | 115 | 16.1 | 13.513 h |
| May | 18.8°C8.8°C | 8.8°C | 70 | 11.1 | 14.915 h |
| June | 21.8°C11.3°C | 11.3°C | 43 | 7.6 | 15.616 h |
| July | 27.1°C14.1°C | 14.1°C | 12 | 2.3 | 15.315 h |
| August, selected | 27.6°C14.6°C | 14.6°C | 14 | 2.6 | 14.114 h |
| September | 24.1°C12.3°C | 12.3°C | 42 | 6.2 | 12.613 h |
| October | 17.0°C8.1°C | 8.1°C | 106 | 11.8 | 11.011 h |
| November | 11.1°C4.2°C | 4.2°C | 174 | 17.3 | 9.610 h |
| December | 7.7°C1.7°C | 1.7°C | 193 | 18.0 | 8.89 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
August in nearby cities
- Beaverton in AugustUnited States · 11 kmHigh 27.1°C · Low 14.2°C · 14 mm rain
- Vancouver, United States in AugustUnited States · 13 kmHigh 26.9°C · Low 14.2°C · 21 mm rain
- Gresham in AugustUnited States · 19 kmHigh 26.1°C · Low 13.9°C · 20 mm rain
- Hillsboro in AugustUnited States · 24 kmHigh 27.1°C · Low 14.4°C · 13 mm rain
- Salem, United States in AugustUnited States · 70 kmHigh 27.9°C · Low 14.1°C · 10 mm rain
- Eugene in AugustUnited States · 167 kmHigh 27.4°C · Low 13.3°C · 12 mm rain
- Tacoma in AugustUnited States · 193 kmHigh 24.3°C · Low 14.2°C · 23 mm rain
- Bend in AugustUnited States · 195 kmHigh 27.2°C · Low 11.3°C · 14 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Portland) is explained once on the Portland year overview and on the Sources, method and limits page.
Beaverton lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.