Hyannis, Cape Cod 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
Good
Best time to visit: July – August
What is the weather like in Hyannis, Cape Cod in August?
In August, Hyannis, Cape Cod is warm: daytime highs average 23 °C, and nights cool down to about 20 °C. The sea averages 21.0 °C – refreshing for a swim. The sun shines for around 8 hours a day. Rain falls on about 9 days, adding up to 74 mm. The air is often humid and muggy. All in all, August is a good month for a holiday in Hyannis, Cape Cod.
August compared
How the weather changes from July to September. Tap a month to open it.
| JulyJul | AugustAug | SeptemberSep | |
|---|---|---|---|
| Score | 66 | 66 | 40 |
| Day | 23° | 23° | 20° |
| Night | 20° | 20° | 17° |
| Sea | 20° | 21° | 19° |
| Sun | 8 h | 8 h | 6 h |
| Rain days | 9 | 9 | 9 |
More details for August
- Daylight
- 13 h 54 min05:49 – 19:43
- UV index
- 8 · very highclear sky, noon (estimate)All months
- Muggy days
- 17 daysdew point 18 °C or moreAll months
- Wind
- 21 km/haverage daily peakAll months
- Cloud cover
- 54 %on averageAll months
- Hot days
- 0 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 35 %68 %
- Seaweight 25 %57 %
- Sunshineweight 20 %75 %
- Few rainy daysweight 20 %66 %
Each factor is rated from 0 to 100 % and weighted for the travel style “Sun, sea & sand”.
What to pack in August
- Swimwear
- Sunscreen
- Sunglasses & sun hat
- Insect repellent
- Rain jacket or umbrella
Hyannis, Cape Cod in August: quick answers
Is Hyannis, Cape Cod hot in August?
Warm rather than hot: in August, daytime highs in Hyannis, Cape Cod average 23 °C and nights cool to about 20 °C.
Can you swim in Hyannis, Cape Cod in August?
Yes. In August the sea averages 21.0 °C – refreshing for a swim.
Does it rain much in Hyannis, Cape Cod in August?
Rain falls on about 9 days, adding up to 74 mm.
Hyannis, Cape Cod month by month
The whole year in Hyannis, Cape CodAll 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