OR · climate averages
Portland Weather by Month
These are climate averages, not a forecast. Station Portland Intl AP (USW00024229), 3.4 miles from downtown, elevation 19 ft.
Portland's warmest month is August (avg high 82.3°F), coldest are January and December (avg low 36.2°F) and wettest is December (5.77 in), per NOAA 1991–2020 climate normals.
- Warmest high August 82.3°F
- Coldest low January and December 36.2°F
- Wettest month December 5.77 in
- Year of rain 12 months 36.92 in
Monthly Averages
Portland's 12 monthly precipitation normals add up to 36.92 inches a year.
July is the driest month, with a precipitation normal of 0.51 inches.
January, February and December are the months with a snowfall normal above 0.1 inch, and they sum to 4.1 inches.
Portland averages 157.0 days a year with at least 0.01 inch of precipitation.
| Month | Avg high | Avg low | Precipitation | Days ≥ 0.01 in | Snow |
|---|---|---|---|---|---|
| January | 47.5°F | 36.2°F | 5.03 in | 18.7 | 1.7 in |
| February | 51.5°F | 36.8°F | 3.68 in | 15.7 | 1.2 in |
| March | 56.8°F | 39.7°F | 3.97 in | 17.8 | 0.1 in |
| April | 62.0°F | 43.7°F | 2.89 in | 17.4 | 0.0 in |
| May | 69.3°F | 49.4°F | 2.51 in | 13.2 | 0.0 in |
| June | 74.3°F | 54.1°F | 1.63 in | 9.2 | 0.0 in |
| July | 81.9°F | 58.5°F | 0.51 in | 3.7 | 0.0 in |
| August | 82.3°F | 58.9°F | 0.54 in | 3.6 | 0.0 in |
| September | 76.7°F | 54.1°F | 1.52 in | 6.7 | 0.0 in |
| October | 64.4°F | 46.7°F | 3.42 in | 13.5 | 0.0 in |
| November | 53.5°F | 40.6°F | 5.45 in | 18.3 | 0.0 in |
| December | 46.9°F | 36.2°F | 5.77 in | 19.2 | 1.2 in |
Warmest, Coldest and Wettest Months
The warmest month is August, with an average high of 82.3°F.
January and December tie for the coldest month, with an average low of 36.2°F.
The wettest month is December, at 5.77 inches of precipitation over about 19.2 days.
In Portland, four months (June, July, August and September) have an average high of at least 70°F.
The range from the lowest average low to the highest average high in Portland is 46.1°F.
In August, the average high in Portland is 23.4°F above the average low.
Best Months to Visit Portland for Weather
May, June, July, August and September meet the weather rule on this page: an average high from 65 to 85°F and precipitation below 3.08 inches.
The rule keeps a month when the average high is from 65 to 85°F and precipitation is below 3.08 inches, the mean of the twelve monthly precipitation normals.
- May · 69.3°F
- June · 74.3°F
- July · 81.9°F
- August · 82.3°F
- September · 76.7°F
Nearby cities
Seattle is the closest other city on this site, 144.0 miles away. Its July average high is 76.5°F, 5.4°F cooler than Portland.
| City | Miles | Avg high | Avg low | Precipitation |
|---|---|---|---|---|
| Seattle | 144.0 | 76.5°F | 56.5°F | 0.78 in |
About This Data
Source: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991–2020. Station: PORTLAND INTL AP (USW00024229), 3.4 mi from downtown, elevation 19 ft. Climate normals are 30-year averages, not forecasts. MonthSky is not affiliated with NOAA.
Palecki, Michael; Durre, Imke; Applequist, Scott; Arguez, Anthony; Lawrimore, Jay (2021). U.S. Climate Normals 2020: U.S. Monthly Climate Normals (1991-2020). NOAA National Centers for Environmental Information. Dataset. https://doi.org/10.25921/wck8-er13. Accessed 2026-10-21.
U.S. Government work.
NOAA and NCEI cannot provide any warranty as to the accuracy, reliability, or completeness of furnished data. Users assume responsibility to determine the usability of these data. The user is responsible for the results of any application of this data for other than its intended purpose.
NOAA and NCEI make no warranty, expressed or implied, regarding these data, nor does the fact of distribution constitute such a warranty. NOAA and NCEI cannot assume liability for any damages caused by any errors or omissions in these data. If appropriate, NCEI can only certify that the data it distributes are an authentic copy of the records that were accepted for inclusion in the NCEI archives.
These pages are built automatically from public NOAA data.
U.S. Monthly Climate Normals (1991-2020) dataset
NCEI dataset landing page for the monthly normals
FAQ
What is the hottest month in Portland?
August is the warmest, with an average high of 82.3°F.
What is the wettest month in Portland?
December is the wettest, at 5.77 inches over about 19.2 days.
How many rainy days does Portland get a year?
The monthly counts of days with at least 0.01 inch of precipitation add up to 157.0 days.
When is the best time to visit Portland for weather?
May, June, July, August and September meet the rule used on this page: average high from 65 to 85°F and precipitation below the monthly mean of 3.08 inches.