Portland Average Rainfall by Month

This page shows the average precipitation (including snowfall) in each month of the year in Portland, Maine. It is based on NOAA data for the years 1991–2020.

Average temperature by month

What's the Rainiest Month in Portland?

In Portland, October has the greatest precipitation of any month. On average, Portland gets 5.2 inches of precipitation in October.

However, May is the month with the greatest chance of precipitation. 40.2% of days in May will have at least some rain.

What's the Driest Month in Portland?

In Portland, July has the least precipitation of any month. On average, Portland gets 3.43 inches of precipitation in July.

August is the month with the lowest chance of precipitation. 30.2% of days in August will have measurable rain.

Month	Precipitation	% Chance
January	3.50 in	36.2
February	3.53 in	35.6
March	4.08 in	36.5
April	4.41 in	37.1
May	3.67 in	40.2
June	4.14 in	38.9
July	3.43 in	34.7
August	3.57 in	30.2
September	3.77 in	31.1
October	5.25 in	35.2
November	4.25 in	35.8
December	4.50 in	39.8
Year	48.09 in	35.9

Weather Station Details

Years	Station	Coordinates
1940–2024	Portland International JetPort	location
1871–1940	Portland	location