Portsmouth weather in August 2025

Expect 81°F daytime maximum temperatures in the shade with on average 9 hours of sunshine per day in Portsmouth in August. Check more long-term weather averages for Portsmouth in August before you book your next holiday to New Hampshire in 2025/2026.

  • 81°F maximum daytime temperature in August in Portsmouth81
    81°F max day temperature
  • 9 hours of sunshine per day
  • 10 days with some rainfall in August in Portsmouth10
    10 days with some rainfall
  • 57°F minimum night-time temperature in August in Portsmouth57
    57°F min night temperature
  • 14 hours of daylight per day in August in Portsmouth14
    14 hours of daylight per day
  • Low heat & humidity in August in PortsmouthL
    Low heat & humidity
  • 2.8 inches monthly rainfall in August in Portsmouth2.8
    2.8 inches of monthly rainfall
  • UV (maximum) index 7 (High) in August in Portsmouth7
    7 (High) UV index
  • 64°F sea temperature in August in Portsmouth64
    64°F sea temperature

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The August weather guide for New Hampshire (Portsmouth) shows long term weather averages processed from data supplied by CRU (University of East Anglia), the Met Office & the Netherlands Meteorological Institute. Find out more about our data sources.

Metric (°C)  |  Imperial (°F)

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How hot is it in Portsmouth in August?

Daytime temperatures usually reach 81°F in Portsmouth in August with low heat and humidity, falling to 57°F at night.

How sunny is it in Portsmouth in August?

There are normally 9 hours of bright sunshine each day in Portsmouth in August - that's 61% of daylight hours.

How warm is the sea around Portsmouth in August?

The average sea temperature around Portsmouth in August is 64°F.

Does it rain in Portsmouth in August?

There are usually 10 days with some rain in Portsmouth in August and the average monthly rainfall is 2.8 inches.

What is the chance of a hurricane in Portsmouth in August?

On average less than 1 day in August in Portsmouth is likely to be affected by the passage of one or more tropical storms.

Portsmouth August sunrise & sunset times

Browse the sunrise and sunset times for Portsmouth in August 2025. Select a month to view Portsmouth sunrise and sunset times for the next 12 months.

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Friday, 1st August 2025 04:34 19:04
Saturday, 16th August 2025 04:50 18:44
Sunday, 31st August 2025 05:07 18:19

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