Portland, Maine weather in May
Temperature, sea and sunshine in May: long-term averages from 30 years of weather data, not a forecast.
Holiday weather in May
Poor
Best time to visit: July – August
What is the weather like in Portland, Maine in May?
In May, Portland, Maine is cool: daytime highs average 16 °C, and nights cool down to about 9 °C. The sea averages 9.1 °C – swimming is only for the hardy. The sun shines for around 7 hours a day. Rain is frequent, with about 10 rainy days and 77 mm in total. All in all, May is not an ideal month for a holiday in Portland, Maine.
May compared
How the weather changes from April to June. Tap a month to open it.
More details for May
- Daylight
- 14 h 41 min05:17 – 19:58
- UV index
- 8 · very highclear sky, noon (estimate)All months
- Muggy days
- 0 daysdew point 18 °C or moreAll months
- Wind
- 18 km/haverage daily peakAll months
- Cloud cover
- 63 %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 %0 %
- Seaweight 25 %0 %
- Sunshineweight 20 %68 %
- Few rainy daysweight 20 %56 %
Each factor is rated from 0 to 100 % and weighted for the travel style “Sun, sea & sand”.
What to pack in May
- Sunscreen
- Sunglasses & sun hat
- A jumper for the evenings
- Rain jacket or umbrella
Portland, Maine in May: quick answers
Is Portland, Maine hot in May?
No. In May, Portland, Maine is cool: daytime highs average 16 °C and nights drop to about 9 °C.
Can you swim in Portland, Maine in May?
Only if you don't mind cold water: in May the sea averages just 9.1 °C. Comfortable swimming temperatures are not reached at any time of year.
Does it rain much in Portland, Maine in May?
Rain is frequent, with about 10 rainy days and 77 mm in total.
Portland, Maine month by month
The whole year in Portland, MaineAll destinations: USAWhere to go in MaySea temperature in May
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