Boston 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: May – September
What is the weather like in Boston in August?
In August, Boston is warm: daytime highs average 26 °C, and nights cool down to about 19 °C. The sea averages 19.0 °C – bracing, so a wetsuit helps for longer swims. The sun shines for around 7 hours a day. Rain is frequent, with about 9 rainy days and 82 mm in total. All in all, August is an excellent month for a holiday in Boston.
August compared
How the weather changes from July to September. Tap a month to open it.
| JulyJul | AugustAug | SeptemberSep | |
|---|---|---|---|
| Score | 83 | 82 | 82 |
| Day | 27° | 26° | 22° |
| Night | 19° | 19° | 15° |
| Sea | 18° | 19° | 18° |
| Sun | 8 h | 7 h | 6 h |
| Rain days | 10 | 9 | 8 |
More details for August
- Daylight
- 13 h 57 min05:51 – 19:48
- UV index
- 8 · very highclear sky, noon (estimate)All months
- Muggy days
- 12 daysdew point 18 °C or moreAll months
- Wind
- 17 km/haverage daily peakAll months
- Cloud cover
- 54 %on averageAll months
- Hot days
- 4 days30 °C or moreAll months
- Snow days
- 0 days1 cm or more of fresh snowAll months
- Time zone
- UTC−4America/New_York
How the score comes together
- Temperatureweight 50 %100 %
- Sunshineweight 20 %68 %
- Few rainy daysweight 30 %62 %
Each factor is rated from 0 to 100 % and weighted for the travel style “City break”.
What to pack in August
- Wetsuit for longer swims
- Sunscreen
- Sunglasses & sun hat
- Light, breathable clothes
- Rain jacket or umbrella
Boston in August: quick answers
Is Boston hot in August?
Warm rather than hot: in August, daytime highs in Boston average 26 °C and nights cool to about 19 °C. On about 4 days the thermometer climbs to 30 °C or more.
Can you swim in Boston in August?
Only if you don't mind cold water: in August the sea averages just 19.0 °C. Comfortable swimming temperatures are not reached at any time of year.
Does it rain much in Boston in August?
Rain is frequent, with about 9 rainy days and 82 mm in total.
Boston month by month
The whole year in BostonAll 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