Boston Weather Averages

Over the course of a year, the weather in Boston, Massachusetts ranges from temperatures in the 90s Fahrenheit (30s Celsius) with thunderstorms to well below freezing with snowstorms. For much of the year though, Boston's climate is relatively mild, thanks to its seaside location.

This page gives detailed information on the annual temperature, precipitation, sun, humidity, wind and storm averages for Boston. The numbers here are historical averages based on climate data gathered at Boston's Logan International Airport, located on the waterfront next to Boston Harbor.

Temperature

59 °F	annual average high	15 °C
45 °F	annual average low	7 °C

Boston's coldest days of the year usually occur in January when the daily maximum temperature averages 36 degrees Fahrenheit (2 degrees Celsius) and the minimum averages 22 °F (-6 °C).

The year's hottest days are normally in mid July. The average temperature peaks then with daily highs of 83 °F (28 °C) and nighttime lows of 67 °F (19 °C).

125 days	70 °F max. or more (21 °C)
92 days	32 °F min. or less (0 °C)

Boston averages 14 days a year when the thermometer reaches into the 90s °F (over 32 °C). The temperature normally doesn't climb above 100 °F (38 °C), even on the hottest days. Typically on 23 days annually the mercury remains below freezing for the entire day.

The thermometer dips to 10 °F (-12 °C) or below on 7 nights a year. Boston averages one day a year when the weather gets as cold as 0 °F (-18 °C).

Precipitation

43.6 in	total precipitation	1107 mm
128 days	of rain or snowfall

December and March are usually the wettest months of the year in Boston, while February and August are the driest.

Snow

49.2 in	total snowfall	125 cm
23 days	with new snow

Most years, it snows in Boston from December to March. On 11 days annually at least an inch (2.5 cm) of snow falls on the city.

Sun

58 %	sunshine
98 days	clear skies

The sun's rays reach the ground in Boston during 58 percent of daylight hours on average year round, for a total of 2590 hours annually. Typically on 98 days a year the sky is mainly clear, with at most 30 percent cloud cover.

Sunlight in Boston lasts for 12 hours and 12 minutes a day on average. The shortest days of the year in mid December have 9 hours and 5 minutes of daylight. The year's longest days in mid June last 15:17 from sunrise to sunset.

Humidity

67 %	average humidity

The annual average for relative humidity in Boston ranges throughout the day from 75 percent at 4:00 am to 58 percent at 1:00 pm.

Local Time	1 am	4 am	7 am	10 am	1 pm	4 pm	7 pm	10 pm
Humidity %	72	75	72	62	58	59	65	69

Wind

12.3 mph

wind speed average

19.8 kph

January, February and March are usually the windiest months for Boston, while the wind is calmest during August.

Storms

10 days	precipitation of 1 inch (25 mm) or more
3 days	snowfall of 5 inches (13 cm) or more
18 days	with thunderstorms a year
5.5 %	chance a named storm makes landfall

Snowstorms that dump 10 inches or more of snow a day are rare in Boston, passing through just once in two years on average.

Thunderstorms usually appear over Boston from March to November, although they can show up in any month.

In any year, there's a 3.2 percent probability that a hurricane will reach land in Suffolk county, which includes Boston. For major hurricanes of category 3 to 5, the likelihood drops to 1.5 percent. Named storms usually arrive during the months of June to October, while hurricanes are generally restricted to August and September.

The chance that a wind gust reaches 40 miles per hour (64 kilometres an hour) or greater is 12.4 percent a year. Intense hurricane force winds that top 115 mph (185 kph) have a 1.2 percent probability of blasting the county.