Late summer · Weather & things to do
Portsmouth in August
Portsmouth's warmest month brings highs averaging 74°F (23°C), lows of 64°F (18°C) and about 3.7 in (94 mm) of rain.
It scores 78/100 for comfort, 3rd of 12, which makes it a solid shoulder-season month.
- Avg high
- 74°F (23°C)
- Avg low
- 64°F (18°C)
- Rain
- 3.7 in (94 mm)
- Humidity
- 81%
- Cloud cover
- 52%
- Daylight
- ~13 h 46 min
- Comfort score
- 78/100 · Great
What August feels like
Highs settle around 74°F (23°C), warm enough for short sleeves.
After dark, temperatures fall to about 64°F (18°C).
Humidity averages 81%, so the air feels sticky and the heat feels stronger than the thermometer says.
Some rain is likely, about 3.7 in (94 mm) in the month, so pack for a shower or two.
Plan around August
August is shoulder season: good weather, a step below the best months (September).
- Last warm month for a while: September highs fall to 69°F.
- Comfort improves from 75/100 in July to 78/100.
- August sits inside the May – Oct window our Boston to Portland route recommends.
What to pack for August
- Light, breathable clothes74°F afternoons
- Sunscreen, sunglasses and a hatstrong sun this month
- Quick-dry fabrics81% average humidity
- Packable rain jacket or umbrellaa shower or two is likely
- Comfortable walking shoesmost picks involve some walking
What to do in Portsmouth in August
August is good outdoor weather here, so these picks lean toward the open air.
Portsmouth Harbor Cruises
Narrated harbor and Isles of Shoals cruises from Ceres Street dock.
Why now Our curated notes say it's best summer.
Strawbery Banke Museum
Ten acres of restored houses spanning 300 years of a waterfront neighborhood.
Why now Our curated notes say it's best May–Oct.
Prescott Park
Waterfront gardens across from Strawbery Banke with harbor views.
Why now August scores 78/100 for comfort, good conditions for being outside.
Ceres Bakery
Long-running downtown bakery for coffee, scones and soup.
Market Square
Brick-lined center of town with shops, cafés and the North Church spire.
Nearby in August
- New Hampshire in August~42 mi · highs 80°F, 3.9 in rain · 4°C (6°F) warmer by day, about as wet
- Portland, Maine in August~48 mi · highs 70°F, 3.7 in rain · 2°C (4°F) cooler by day, about as wet
- Boston in August~51 mi · highs 82°F, 3.7 in rain · 4°C (8°F) warmer by day, about as wet
- White Mountains in August~87 mi · highs 56°F, 4.4 in rain · 10°C (18°F) cooler by day, wetter
NASA POWER 2001–2025 monthly averages on a ~50 km grid. Comfort scores weigh temperature, rain, humidity and cloud: see how we score each month. Check a forecast before you go.
Portsmouth in August: quick answers
Is August a good time to visit Portsmouth?
It's a good shoulder-season choice, scoring 78/100 against a best of 88 in September. Expect highs of 74°F (23°C) and 3.7 in (94 mm) of rain. August is inside the May – Oct window our Boston to Portland route recommends.
How hot is Portsmouth in August?
Average highs are 74°F (23°C) and average lows 64°F (18°C), making it the warmest month by daytime highs.
Does it rain a lot in Portsmouth in August?
Some: about 3.7 in (94 mm) of rain falls across August on average, the 3rd-driest month of the year. The annual total is about 52.6 in (1337 mm).
What should I pack for Portsmouth in August?
Bring light, breathable clothes (74°F afternoons), sunscreen, sunglasses and a hat (strong sun this month), quick-dry fabrics (81% average humidity), packable rain jacket or umbrella (a shower or two is likely) and comfortable walking shoes (most picks involve some walking).
Routes in season in August
- Boston to Portland May – Oct
Planning Portsmouth in August?
Share this August plan with your group, poll everyone on dates and keep the packing list in one place.