Portland Temperatures: Averages by Month





The numbers here tell you how hot and cold the weather usually is in Portland, Maine during each month of the year.

The average high and low temperatures are listed below monthly and annually for the city, in both degrees Fahrenheit and Celsius.

Maximums and minimums are only part of the temperature picture. To fill in the rest, there's information on how many days a month get above or below a given temperature.

To find out how often it rises over 70, 80 or 90 °F each month in Portland, scroll down farther. There are also monthly and yearly counts of days with cold weather.

All the numbers are long-term historical averages based on climate data gathered from 1981 to 2010.

Average Portland temperatures
High °F Low °F   High °C Low °C
31 13 January 0 -10
35 16 February 1 -9
42 25 March 6 -4
53 35 April 12 2
64 44 May 18 7
73 54 June 23 12
79 59 July 26 15
78 58 August 25 15
70 50 September 21 10
59 39 October 15 4
48 31 November 9 -1
37 20 December 3 -6
56 37 Year 13 3

Days of Hot Weather in Portland

Portland doesn't often get really hot, averaging just four days a year with temperatures in the 90s Fahrenheit. And it's not expected to reach 100 °F (38 °C) here. But that 90-degree weather can appear anytime from May to September, although it's most likely to occur in July.

Number of days in Portland of at least 70, 80 or 90 °F
  70 °F
21 °C
80 °F
27 °C
90 °F
32 °C
January 0 0 0
February 0 0 0
March 0 0 0
April 1 0 0
May 7 2 0
June 20 7 1
July 28 13 2
August 28 11 1
September 14 3 0
October 3 0 0
November 0 0 0
December 0 0 0
Year 101 36 4

How Often Portland Has Cold Temperatures

Portland typically has 142 frosty nights a year. Most nights from December to March are below 32 °F and normally seven of those drop to 0 °F (-18 °C) or less.

For an average of 40 days annually the thermometer never rises above freezing. Days that chilly can occur from November to April, including half the days in January.

Days per month on average in Portland when the minimum temperature drops to 32, 20 or 10 °F or below
  10 °F
-12 °C
20 °F
-8 °C
32 °F
0 °C
January 12 22 30
February 8 17 26
March 2 8 24
April 0 0 10
May 0 0 1
June 0 0 0
July 0 0 0
August 0 0 0
September 0 0 0
October 0 0 7
November 0 2 18
December 5 15 27
Year 28 65 142
Reference

National Climatic Data Center. NOAA's 1981-2010 Climate Normals.

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