Seattle weather in August
Temperature, sea and sunshine in August: long-term averages from 30 years of weather data, not a forecast.
Holiday weather in August
Excellent
Best time to visit: July – September
What is the weather like in Seattle in August?
In August, Seattle is warm: daytime highs average 24 °C, and nights cool down to about 14 °C. The sea averages 11.8 °C – swimming is only for the hardy. The sun shines for around 9 hours a day. Rain falls on about 5 days, adding up to 37 mm. All in all, August is an excellent month for a holiday in Seattle.
August compared
How the weather changes from July to September. Tap a month to open it.
| JulyJul | AugustAug | SeptemberSep | |
|---|---|---|---|
| Score | 97 | 96 | 82 |
| Day | 24° | 24° | 21° |
| Night | 14° | 14° | 11° |
| Sea | 11° | 12° | 11° |
| Sun | 10 h | 9 h | 7 h |
| Rain days | 5 | 5 | 9 |
More details for August
- Daylight
- 14 h 20 min06:04 – 20:24
- UV index
- 7 · highclear sky, noon (estimate)All months
- Muggy days
- 0 daysdew point 18 °C or moreAll months
- Wind
- 12 km/haverage daily peakAll months
- Cloud cover
- 44 %on averageAll months
- Hot days
- 2 days30 °C or moreAll months
- Snow days
- 0 days1 cm or more of fresh snowAll months
- Time zone
- UTC−7America/Los_Angeles
How the score comes together
- Temperatureweight 50 %100 %
- Sunshineweight 20 %95 %
- Few rainy daysweight 30 %91 %
Each factor is rated from 0 to 100 % and weighted for the travel style “City break”.
What to pack in August
- Sunscreen
- Sunglasses & sun hat
- A jumper for the evenings
Seattle in August: quick answers
Is Seattle hot in August?
Warm rather than hot: in August, daytime highs in Seattle average 24 °C and nights cool to about 14 °C. On about 2 days the thermometer climbs to 30 °C or more.
Can you swim in Seattle in August?
Only if you don't mind cold water: in August the sea averages just 11.8 °C. Comfortable swimming temperatures are not reached at any time of year.
Does it rain much in Seattle in August?
Rain falls on about 5 days, adding up to 37 mm.
Seattle month by month
The whole year in SeattleAll destinations: USAWhere to go in AugustSea temperature in August
Climate averages 1996–2025, not a forecast. Data: Copernicus ERA5 / ERA5-Land via Open-Meteo.com (CC BY 4.0), NOAA OISST, WMO 1991–2020 (NOAA NCEI), GeoNames (CC BY 4.0). Sources & licences