Portland weather in May 2026

Expect daytime maximum temperatures of 18°C in Portland, Maine in May based on long-term weather averages. There are 8 hours of sunshine per day on average with 12 days with some rainfall and typically 92 mm of rainfall in the month.

  • 18°C maximum daytime temperature in May in Portland18
    18°C max day temperature
  • 8 hours of sunshine per day
  • 12 days with some rainfall in May in Portland12
    12 days with some rainfall
  • 6°C minimum night-time temperature in May in Portland6
    6°C min night temperature
  • 15 hours of daylight per day in May in Portland15
    15 hours of daylight per day
  • No heat & humidity in May in Portland0
    No heat & humidity
  • 92 mm monthly rainfall in May in Portland92
    92 mm of monthly rainfall
  • UV (maximum) index 7 (High) in May in Portland7
    7 (High) UV index
  • 8°C sea temperature in May in Portland8
    8°C sea temperature

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The May weather guide for Maine (Portland) 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 / mm)  |  Imperial (°F / inches)

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How hot is it in Portland in May?

Daytime temperatures usually reach 19°C in Portland in May, falling to 6°C at night.

How sunny is it in Portland in May?

There are normally 7 hours of bright sunshine each day in Portland in May - that's 49% of daylight hours.

Does it rain in Portland in May?

There are usually 12 days with some rain in Portland in May and the average monthly rainfall is 93mm.

Portland May sunrise & sunset times

Browse the sunrise and sunset times for Portland in May 2026. Select a month to view Portland sunrise and sunset times for the next 12 months.

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Friday, 1st May 2026 04:33 18:44
Saturday, 16th May 2026 04:15 19:01
Sunday, 31st May 2026 04:03 19:15

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