SeasonMapHyannis (Cape Cod) weather in August
United States
August in Hyannis: hot, a little rain, with muggy air — one of the best months to visit.
#2 of 12 months in Hyannis · #325 of 1383 destinations to visit in August · comfort 88/100 (tier A)
Updated September 2026 · climate normals from ERA5 reanalysis
Traveller notes on Hyannis in August
No notes yet. Open Hyannis on the map to add the first one.
Hyannis climate normals — August
| Daytime high | 27°C / 80°F | 🥵 hot |
|---|---|---|
| Nighttime low | 18°C / 65°F | |
| Feels like (high) | 29°C / 84°F | |
| Sea temperature | 25°C / 77°F | 😎 warm sea |
| Rainfall | 79 mm / 3.1 in | 🌦 some rain |
| Rainy days | 7 days | |
| Humidity | 81% | 💦 very humid |
| Dew point | 18°C / 65°F | |
| Sunshine | 10.8 h/day | |
| Daylight | 13.8 h | |
| Wind | 21 km/h / 13 mph | |
| Air quality (US AQI) | 58 | 🙂 moderate |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
Crowds in Hyannis in August
How busy the place itself is — school and mass holidays, the months an editor tagged, and how sought-after the weather makes them. Never part of the comfort score.
Peak crowdsIsland ferry high season, Peak summer season, Summer break in United States(estimated)
Peak crowdsBusyShoulder seasonQuiet
Best months for Hyannis's weather
Ranked by this destination's own climate comfort score across the year — a different thing from how busy it gets (see Crowds above).
Best weatherHyannis's weather peaks June–August, best around July.
August includes White shark season.
Best weatherFair weatherToughest weather
What's on in Hyannis in August
Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.
- Opening
Island ferry high season
20 May – 15 Oct · usuallySummer season opensCrowdedBook earlyHyannis is the mainland end of the Nantucket boats, and the summer timetable adds fast ferries and extra sailings from late May. Car spaces on the traditional boat are released months ahead and go the day they open. Source ↗
- Nature
White shark season
1 Jun – 31 Oct · usuallyWildlife seasonRiskWhite sharks follow the grey seals into Cape waters from early summer and are gone by late autumn, with the tagged detections peaking in August and September. It is the ocean side that closes for sightings, not the calmer Nantucket Sound beaches in town. Source ↗
- Season
Peak summer season
1 Jul – 31 AugSchool holidaysCrowdedBook earlyThe whole Cape funnels through here for the boats, and Route 6 and the rotaries jam every Friday afternoon and Sunday evening. Main Street is at its best on a weekday morning before the day-boats land.
- Hazard
Hurricane season
15 Aug – 31 Oct · usuallyClosuresNew England catches the tail of Atlantic systems in late summer and autumn, and even a passing storm cancels the island ferries and takes the power out for a day or two. Direct hits are rare; disrupted travel is not. Source ↗
Nearby, and something's on
Within 300 km of Hyannis — a day trip or a short hop — with something on this month. Never part of the comfort score.
Where is Hyannis?
Hyannis in August — FAQ
- Is August a good time to visit Hyannis?
- August in Hyannis: hot, a little rain, with muggy air — one of the best months to visit. It ranks #2 of 12 months for Hyannis on SeasonMap's comfort score (88/100).
- What is the weather like in Hyannis in August?
- In August, Hyannis averages a daily high of 26.8°C and a low of 18.1°C, with about 78.6 mm of rain over roughly 6.9 rainy days.
- What is the air quality in Hyannis in August?
- Hyannis has a mean US Air Quality Index of about 58 in August.
Other months in Hyannis
Compare Hyannis in August
Warmer or cooler than Hyannis in August
Similar destinations in North America — August
Within 300 km: Newport's Newport Jazz Festival on 31 Jul – 2 Aug, and Boston's Whales on Stellwagen Bank around 15 Apr – 20 Oct.