| Month | High | Low | Rain | Wet days | Score |
|---|---|---|---|---|---|
| January | 9° | 2.8° | 124.9mm | 18.5 | 35 |
| February | 9.8° | 2.6° | 84.3mm | 15 | 37 |
| March | 12.2° | 4.2° | 92.3mm | 17 | 45 |
| April | 15° | 6.3° | 61.2mm | 14.2 | 56 |
| May | 18.8° | 9.6° | 44.8mm | 11 | 74 |
| June | 21.7° | 12.4° | 30.3mm | 8.4 | 83 |
| July | 25.3° | 14.6° | 9.2mm | 3.2 | 94 |
| August | 25.1° | 14.8° | 17mm | 3.9 | 92 |
| September | 21.7° | 12.4° | 36mm | 8 | 84 |
| October | 16° | 8.3° | 84mm | 14.3 | 59 |
| November | 11.3° | 4.5° | 138.8mm | 17.7 | 42 |
| December | 8.5° | 2.6° | 129.8mm | 18 | 33 |
January in Seattle averages a daily high of 9°C with nights around 2.8°C. Expect roughly 18.5 wet days totalling 124.9mm. Demanding conditions — pack for it and plan indoor options.
February in Seattle averages a daily high of 9.8°C with nights around 2.6°C. Expect roughly 15 wet days totalling 84.3mm. Demanding conditions — pack for it and plan indoor options.
March in Seattle averages a daily high of 12.2°C with nights around 4.2°C. Expect roughly 17 wet days totalling 92.3mm. Demanding conditions — pack for it and plan indoor options.
April in Seattle averages a daily high of 15°C with nights around 6.3°C. Expect roughly 14.2 wet days totalling 61.2mm. Generally workable, with some weather to plan around.
May in Seattle averages a daily high of 18.8°C with nights around 9.6°C. Expect roughly 11 wet days totalling 44.8mm. Generally workable, with some weather to plan around.
June in Seattle averages a daily high of 21.7°C with nights around 12.4°C. Expect roughly 8.4 wet days totalling 30.3mm. Comfortable conditions for being outdoors all day.
July in Seattle averages a daily high of 25.3°C with nights around 14.6°C. Expect roughly 3.2 wet days totalling 9.2mm. Comfortable conditions for being outdoors all day.
August in Seattle averages a daily high of 25.1°C with nights around 14.8°C. Expect roughly 3.9 wet days totalling 17mm. Comfortable conditions for being outdoors all day.
September in Seattle averages a daily high of 21.7°C with nights around 12.4°C. Expect roughly 8 wet days totalling 36mm. Comfortable conditions for being outdoors all day.
October in Seattle averages a daily high of 16°C with nights around 8.3°C. Expect roughly 14.3 wet days totalling 84mm. Generally workable, with some weather to plan around.
November in Seattle averages a daily high of 11.3°C with nights around 4.5°C. Expect roughly 17.7 wet days totalling 138.8mm. Demanding conditions — pack for it and plan indoor options.
December in Seattle averages a daily high of 8.5°C with nights around 2.6°C. Expect roughly 18 wet days totalling 129.8mm. 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. Seattle peaks at 94.
Based on 30 years of records, July–August scores highest for comfort in Seattle, balancing daytime temperature against rainfall.
July is the warmest, averaging a daily high of 25.3°C.
November is the wettest, averaging 138.8mm of rain across roughly 17.7 wet days.
December is the coolest month, with average daily highs around 8.5°C.