Get the monthly weather forecast for Portland, ME, including daily high/low, historical averages, to help you plan ahead.

In Portland during May average daily high temperatures increase from 58°F to 67°F and it is overcast or mostly cloudy about 56% of the time.

May's highs tend to be in the low 60s, with the lowest temperatures in the 40s. Like autumn, spring also sees notable precipitation, with a little more than 4 ...

Get the monthly weather forecast for South Portland, ME, including daily high/low, historical averages, to help you plan ahead.

Temperature records began November 25, 1940. Portland, ME Daily Records for MAY. High Temperatures. Record High. Record Cool High. Page 2. Date Record. Year(s).

Portland, Maine experiences a range of temperatures in May. The average temperature during this month is around 53.2°F (11.8°C).

Rain early. Decreasing clouds overnight. Low 34F. Winds NW at 15 to 25 mph. Chance of rain 100%. Higher wind gusts possible. Record Low6°. Average Low28°.

Over the course of the year, the temperature typically varies from 16°F to 78°F and is rarely below 1°F or above 87°F. Climate in Portland. Link. Download.

Portland weather in May 2025. Expect 18°C daytime maximum temperatures in the shade with on average 8 hours of sunshine per day in Portland in May.