| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | 0.3° | -9° | 93mm | 11.3 | 7 |
| February | 1.8° | -8.2° | 88.8mm | 10 | 10 |
| March | 5.8° | -3.6° | 100.8mm | 11 | 24 |
| April | 12° | 1.6° | 111.4mm | 11.2 | 51 |
| May | 17.8° | 7.2° | 91.6mm | 12 | 69 |
| June | 22.8° | 12.5° | 108mm | 11.8 | 76 |
| July | 26.3° | 15.9° | 94.1mm | 11 | 78 |
| August | 25.8° | 15.2° | 87.1mm | 9.5 | 81 |
| September | 21.8° | 11° | 92.4mm | 9.1 | 82 |
| October | 15.4° | 4.9° | 141.8mm | 10.6 | 64 |
| November | 9.1° | -0.6° | 106.6mm | 10.3 | 41 |
| December | 3.5° | -5.5° | 115.9mm | 12.5 | 11 |
January in Portland averages a daily high of 0.3°C with nights around -9°C. Expect roughly 11.3 wet days totalling 93mm. A hard month to visit for comfort alone.
February in Portland averages a daily high of 1.8°C with nights around -8.2°C. Expect roughly 10 wet days totalling 88.8mm. A hard month to visit for comfort alone.
March in Portland averages a daily high of 5.8°C with nights around -3.6°C. Expect roughly 11 wet days totalling 100.8mm. A hard month to visit for comfort alone.
April in Portland averages a daily high of 12°C with nights around 1.6°C. Expect roughly 11.2 wet days totalling 111.4mm. Demanding conditions — pack for it and plan indoor options.
May in Portland averages a daily high of 17.8°C with nights around 7.2°C. Expect roughly 12 wet days totalling 91.6mm. Generally workable, with some weather to plan around.
June in Portland averages a daily high of 22.8°C with nights around 12.5°C. Expect roughly 11.8 wet days totalling 108mm. Comfortable conditions for being outdoors all day.
July in Portland averages a daily high of 26.3°C with nights around 15.9°C. Expect roughly 11 wet days totalling 94.1mm. Comfortable conditions for being outdoors all day.
August in Portland averages a daily high of 25.8°C with nights around 15.2°C. Expect roughly 9.5 wet days totalling 87.1mm. Comfortable conditions for being outdoors all day.
September in Portland averages a daily high of 21.8°C with nights around 11°C. Expect roughly 9.1 wet days totalling 92.4mm. Comfortable conditions for being outdoors all day.
October in Portland averages a daily high of 15.4°C with nights around 4.9°C. Expect roughly 10.6 wet days totalling 141.8mm. Generally workable, with some weather to plan around.
November in Portland averages a daily high of 9.1°C with nights around -0.6°C. Expect roughly 10.3 wet days totalling 106.6mm. Demanding conditions — pack for it and plan indoor options.
December in Portland averages a daily high of 3.5°C with nights around -5.5°C. Expect roughly 12.5 wet days totalling 115.9mm. A hard month to visit for comfort alone.
Each month scores out of 100. It starts at 100 and loses points for daytime highs outside a 20–27°C band, for wet days, and for nights below 2°C. Nothing else is weighted in — no crowd data, no prices, no opinion. Portland peaks at 82.
Based on 30 years of records, June–September scores highest for comfort in Portland, balancing daytime temperature against rainfall.
July is the warmest, averaging a daily high of 26.3°C.
October is the wettest, averaging 141.8mm of rain across roughly 10.6 wet days.
January is the coolest month, with average daily highs around 0.3°C.