Early July to late August for peak warm dry weather; September–October for fewer crowds with lingering summer conditions and lower hotel rates.. July and August are Seattle's driest months (0.7–0.9 inches of rain) with average highs in the mid-to-upper 70s°F and long daylight hours. Seafair and peak outdoor activity season coincide. September offers a 'sweet spot' — summer weather lingers as crowds thin and hotel rates drop
| Month | High (°F) | Low (°F) | Notes |
|---|---|---|---|
| Jan | 46 | 36 | cool & wet |
| Feb | 48 | 36 | cool & changeable |
| Mar | 52 | 38 | cool & wet |
| Apr | 57 | 41 | cool & wet |
| May | 65 | 48 | mild & changeable |
| Jun | 70 | 53 | mild & changeable |
| Jul | 77 | 57 | warm & mostly dry |
| Aug | 77 | 58 | warm & mostly dry |
| Sep | 70 | 54 | mild & changeable |
| Oct | 59 | 47 | cool & changeable |
| Nov | 50 | 41 | cool & wet |
| Dec | 44 | 36 | crisp & wet |