Climateby Month

Boston, MA climate by month

NOAA 1991-2020 normals · 48 ft elevation · also covers Cambridge, Lynn

Summers in Boston are warm and often humid; winters are cold and snowy. Highs peak at 82°F in July and fall to 37°F in January. Wet days are spread through the year, from about 9 to 12 a month. Normal snowfall is about 49 in a year. The most comfortable time to visit is May, June and September.

Warmest month
82°F
July normal high
Coldest month
23°F
January normal low
Wet days a year
128
43.6 in of precipitation
Snow a year
49.2 in
normal snowfall

How warm is Boston?

Normal highs range from 37°F in January to 82°F in July.

20°40°60°80°100° January: normal high 37°F (3°C), low 23°F (-5°C) 37° 23° February: normal high 39°F (4°C), low 25°F (-4°C) March: normal high 46°F (8°C), low 31°F (-1°C) April: normal high 56°F (13°C), low 41°F (5°C) May: normal high 67°F (19°C), low 50°F (10°C) June: normal high 76°F (24°C), low 60°F (16°C) July: normal high 82°F (28°C), low 66°F (19°C) 82° 66° August: normal high 80°F (27°C), low 65°F (18°C) September: normal high 73°F (23°C), low 58°F (14°C) October: normal high 62°F (17°C), low 48°F (9°C) November: normal high 52°F (11°C), low 38°F (3°C) December: normal high 42°F (6°C), low 29°F (-2°C) JFMAMJJASOND

Bars run from the normal low to the normal high for each month.

How rainy is Boston?

December has the most wet days (about 12); the year brings about 44 in of precipitation.

January: 12 wet days February: 11 wet days March: 12 wet days April: 12 wet days May: 12 wet days June: 11 wet days July: 9 wet days August: 9 wet days 9 September: 9 wet days October: 11 wet days November: 10 wet days December: 12 wet days 12 JFMAMJJASOND

Wet day: at least 0.01 in of rain or melted snow, counted from daily records 1991-2020.

How much does it snow?

Normal snowfall is 49.2 in a year, most of it in February.

January: 14.3 in of snow February: 14.4 in of snow 14.4 March: 9.0 in of snow April: 1.6 in of snow May: 0.0 in of snow 0.0 June: 0.0 in of snow July: 0.0 in of snow August: 0.0 in of snow September: 0.0 in of snow October: 0.2 in of snow November: 0.7 in of snow December: 9.0 in of snow JFMAMJJASOND

How humid is Boston?

Muggy days peak in July, at about 10 days.

January: 0 muggy days 0 February: 0 muggy days March: 0 muggy days April: 0 muggy days May: 0 muggy days June: 3 muggy days July: 10 muggy days 10 August: 9 muggy days September: 4 muggy days October: 0 muggy days November: 0 muggy days December: 0 muggy days JFMAMJJASOND

Muggy day: daily mean dew point of 65°F or higher, from hourly observations 1991-2020 at Gen E L Logan International Airport, 2.5 mi E of the city center.

How much daylight?

Daylight ranges from about 9.1 hours in December to 15.2 hours in June.

January: 9.5 hours of daylight February: 10.6 hours of daylight March: 11.9 hours of daylight April: 13.4 hours of daylight May: 14.6 hours of daylight June: 15.2 hours of daylight 15.2 July: 14.9 hours of daylight August: 13.8 hours of daylight September: 12.5 hours of daylight October: 11.1 hours of daylight November: 9.8 hours of daylight December: 9.1 hours of daylight 9.1 JFMAMJJASOND
See all numbers
Monthly climate normals and day counts for Boston, 1991-2020
MonthHighLowPrecip.Wet daysSnowMuggy daysDaylight
January 37°F23°F 3.4 in12 14.3 in 0 9.5 h
February 39°F25°F 3.2 in11 14.4 in 0 10.6 h
March 46°F31°F 4.2 in12 9.0 in 0 11.9 h
April 56°F41°F 3.6 in12 1.6 in 0 13.4 h
May 67°F50°F 3.3 in12 0.0 in 0 14.6 h
June 76°F60°F 3.9 in11 0.0 in 3 15.2 h
July 82°F66°F 3.3 in9 0.0 in 10 14.9 h
August 80°F65°F 3.2 in9 0.0 in 9 13.8 h
September 73°F58°F 3.6 in9 0.0 in 4 12.5 h
October 62°F48°F 4.0 in11 0.2 in 0 11.1 h
November 52°F38°F 3.7 in10 0.7 in 0 9.8 h
December 42°F29°F 4.3 in12 9.0 in 0 9.1 h

High and low: NOAA 1991-2020 normal daily high and low. Wet days: at least 0.01 in of rain or melted snow. Muggy days: daily mean dew point 65°F or higher.

Best months to visit Boston

By our comfort score, the best months are May, June and September.

Comfort score by month (0-100) and its parts, in days per month
MonthScoreComfortableNotable rainHot or cold
Jan 280720
Feb 320616
Mar 421710
Apr 57671
May 711471
Jun 681273
Jul 59666
Aug 60854
Sep 681561
Oct 581060
Nov 43363
Dec 310713

Score = 40 × share of comfortable days + 25 × share of days without notable rain + 20 × share of days neither hot (90°F+) nor cold (high 40°F or below) + 15 × daylight. How the score works.

Frost dates in Boston

The last spring frost typically comes around Apr 4, and the first fall frost around Nov 9, leaving 218 frost-free days in a typical year.

Frost and freeze dates for Boston
Typical date1 year in 10
Last spring frost (32°F)Apr 4after Apr 17
First fall frost (32°F)Nov 9before Oct 29
Last hard freeze (28°F)Mar 28after Apr 6
First hard freeze (28°F)Nov 21before Nov 8
Frost-free season218 daysunder 201 days

"Typical" is the date with a 50% chance of a later spring frost (or earlier fall frost). Planting after the "1 year in 10" spring date gives a 90% chance of no further frost. The Old Farmer's Almanac publishes 30% dates, which fall between our typical and 1-in-10 dates.

Station: Boston Logan Intl Airport (USW00014739), NOAA 1991-2020 freeze probabilities. Frost dates for every city in Massachusetts.

Hottest and coldest readings, 1991-2020

The highest reading was 103°F (July 22, 2011); the lowest was -9°F (February 14, 2016).

From the temperature station's daily records with NOAA quality flags removed. Not an all-time record.

Near Boston

Similar climates elsewhere

Also covers

Cambridge and Lynn use the same temperature and rain stations as Boston, so their monthly numbers are the ones on this page.

Where the numbers come from

  • Temperature, rain, snowfall, frost dates, humidity and wind by hour and cloud cover: Boston Logan Intl Airport (USW00014739), 2.5 mi E of the city center, 12 ft . NOAA normals and daily records, 1991-2020.
  • Snow depth: Hingham (USC00193624), 12 mi SE of the city center, 35 ft . NOAA normals and daily records, 1991-2020.
  • Daily humidity and wind: Gen E L Logan International Airport (725090-14739), 2.5 mi E of the city center, 11 ft . Hourly observations, 1991-2020.

Distances from the city center (USGS). Methodology · Report an error