Boston Weather in May

Boston, Massachusetts has pleasantly mild weather in May. Most days have temperatures over 60 degrees Fahrenheit (16 degrees Celsius). But the rain falls more often in May than it does in other months.

This page gives detailed information on the typical May temperature, precipitation, sun, humidity, wind and storms 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

67 °F	May average high	19 °C
50 °F	May average low	10 °C

12 days	70 °F max. or more (21 °C)
18 days	50 °F min. or less (10 °C)

Nearly every day in May warms to over 50 °F (10 °C) in Boston. The city averages 4 days this month when the thermometer reaches into the 80s °F (over 26 °C). The temperature can rise above 90 °F (32 °C) during May, but that doesn't happen every year.

This month the thermometer dips to 40 °F (4 °C) or below for an average of one night. But May does not normally get as cold as 32 °F (0 °C).

Rain

3.3 in	total precipitation	83 mm
12 days	of rain

Half the time, Boston receives 2.3 to 3.5 inches (59 to 88 mm) of rainfall in May. One in four years has drier weather, while another one in four is wetter. None of the precipitation falls as snow.

Sun

58 %	sunshine
6 days	clear skies

The sun's rays reach the ground in Boston during 58 percent of daylight hours on average in May, for a total of 262 hours in the month. Typically on 6 days this month the sky is mainly clear, with at most 30 percent cloud cover. May has fewer clear days than any other month here.

Sunlight in May at Boston lasts for 14 hours and 37 minutes a day on average. The shortest day of the month is the 1st with 14 hours and 5 minutes of daylight. By the end of the month, the days have lengthened to 15:04 from sunrise to sunset. These durations can vary by a minute or two from year to year.

Humidity

97 %	May average humidity

The relative humidity in Boston during May usually peaks at 77 percent in the morning then drops to 58 percent by early afternoon.

Local Time	1 am	4 am	7 am	10 am	1 pm	4 pm	7 pm	10 pm
Humidity %	74	77	71	61	58	58	64	70

Wind

12.0 mph

May wind speed average

19.3 kph

May is an average month in Boston for wind speed.

Storms

2 days	rainfall of 0.5 inches (13 mm) or more
2 days	with thunderstorms in May

With winter over and the tropical storm season yet to begin, any storms passing through Boston during May are rain or thunderstorms.