May weather forecast and climate
Boston, MA

A beautiful natural park with the George Washington Monument in Boston, Massachusetts, with a sneak view of the city skyscrapers
A beautiful natural park with the George Washington Monument in Boston, Massachusetts, with a sneak view of the city skyscrapers
The last month of the spring, May, is a comfortable month in Boston, Massachusetts, with temperature in the range of an average high of 66.4°F (19.1°C) and an average low of 50°F (10°C).

Temperature

In Boston, the average high-temperature in May increases, from a cool 55.2°F (12.9°C) in April, to a comfortable 66.4°F (19.1°C). In Boston, Massachusetts, the average low-temperature is 50°F (10°C).

Humidity

The average relative humidity in Boston is 72%.

Rainfall

In May, the rain falls for 15.3 days. Throughout May, 1.81" (46mm) of precipitation is accumulated. In Boston, during the entire year, the rain falls for 141.4 days and collects up to 27.2" (691mm) of precipitation.

Snowfall

Months with snowfall in Boston are January through May, October through December. May is the last month it regularly snows in Boston. During 0.1 snowfall days, in May, Boston aggregates 0.04" (1mm) of snow. Throughout the year, in Boston, there are 29.8 snowfall days, and 15.75" (400mm) of snow is accumulated.

Ocean temperature

In Boston, the average seawater temperature is 49.1°F (9.5°C).
Note: Swimming in 49.1°F (9.5°C) is considered dangerous. Unprotected immersion in temperatures below 50°F (10°C) causes quickly maximum intensity cold shock with hyperventilation.

Daylight

In May, the average length of the day is 14.6h.

Sunshine

In Boston, the average sunshine in May is 8.3h.

UV index

In Boston, the average daily maximum UV index in May is 5. A UV Index value of 3 to 5 symbolizes a moderate threat to health from the exposure to the Sun's UV rays for average individuals.
Note: The average daily UV index of 5 transform into the following instructions:
Take precautions - Protection against sunburn is recommended. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. Beware! The strength of the UV rays is increased nearly double-fold by the reflection of the snow.

What is the temperature in May in Boston?

The average high-temperature, in May, in Boston, is 66.4°F (19.1°C), while the average low-temperature is 50°F (10°C).

What is the average humidity in May in Boston?

In Boston, Massachusetts, the average relative humidity in May is 72%.

How much does it rain in Boston in May?

In May, in Boston, Massachusetts, the rain falls for 15.3 days. Throughout May, 1.81" (46mm) of precipitation is accumulated.

What is the last month it snows in Boston?

May is the last month it regularly snows. During 0.1 snowfall days, in May, Boston aggregates 0.04" (1mm) of snow.

What is the ocean temperature in May in Boston?

In May, the average ocean temperature in Boston, Massachusetts, is 49.1°F (9.5°C). Swimming in 49.1°F (9.5°C) is considered life-threatening. Even a few minutes in 55.4°F (13°C) water is uncomfortable, and swimming below 50°F (10°C) may cause total loss of breathing control and cold shock, depending on a person's physique.

How many hours of daylight does Boston have in May?

In Boston, the average length of the day in May is 14.6h.

How many hours of sunshine does Boston have in May?

In Boston, the average sunshine in May is 8.3h.

What is the UV index intensity in May in Boston?

In May, the average daily maximum UV index in Boston is 5. A UV Index of 3 to 5 symbolizes a moderate vulnerability from unprotected exposure to the UV radiation.
Average temperature in May - Boston, MA
  • Average high temperature in May: 19.1°C

The warmest month (with the highest average high temperature) is July (27.6°C).
The month with the lowest average high temperature is January (1.2°C).

  • Average low temperature in May: 10°C

The month with the highest average low temperature is July (18.3°C).
The coldest month (with the lowest average low temperature) is January (-5.2°C).

Average pressure in May - Boston, MA
  • Average pressure in May: 1016.1mbar

The month with the highest atmospheric pressure is November (1018.1mbar).
The month with the lowest atmospheric pressure is June (1013.4mbar).

Average wind speed in May - Boston, MA
  • Average wind speed in May: 11.9km/h

The windiest month (with the highest average wind speed) is January (15.9km/h).
The calmest month (with the lowest average wind speed) is August (9.9km/h).

Average humidity in May - Boston, MA
  • Average humidity in May: 72%

The month with the highest relative humidity is February (77%).
The month with the lowest relative humidity is April (69%).

Average rainfall in May - Boston, MA
  • Average rainfall in May: 46mm

The wettest months (with the highest rainfall) are March, April and December (74mm).
The driest month (with the least rainfall) is September (32mm).

Average rainfall days in May - Boston, MA
  • Average rainfall days in May: 15.3 days

The month with the highest number of rainy days is May (15.3 days).
The month with the least rainy days is January (7.9 days).

Average snowfall in May - Boston, MA
  • Average snowfall in May: 1mm

The month with the highest snowfall is February (120mm).
Months with the least snowfall are June, July, August and September (0mm).

Average snowfall days in May - Boston, MA
  • Average snowfall days in May: 0.1 days

Months with the highest number of snowfall days are January and February (7.6 days).
Months with the least snowfall days are June, July, August and September (0 days).

Average sea temperature in May - Boston, MA
  • Average sea temperature in May: 9.5°C

The best month for swimming (with the highest average sea temperature) is August (20°C).
The coldest month (with the lowest average sea temperature) is February (3.4°C).

Average daylight in May / Average sunshine in May - Boston, MA
  • Average daylight in May: 14.6h

The month with the longest days is June (Average daylight: 15.2h).
The month with the shortest days is December (Average daylight: 9.1h).

  • Average sunshine in May: 8.3h

The month with the most sunshine is August (Average sunshine: 10.5h).
The month with the least sunshine is February (Average sunshine: 4.6h).

Average sunshine days in May - Boston, MA
  • Average sunshine days in May: 14.2 days

The month with the most sunshine days is September (17.7 days).
The month with the least sunshine days is April (13 days).

Average UV index in May - Boston, MA
  • Average UV index in May: 5

Months with the highest UV index are June, July and August (UV index 6).
Months with the lowest UV index are January, February, March, November and December (UV index 2).

Average cloud cover in May - Boston, MA
  • Average cloud cover in May: 46

The month with the most cloud cover is March (Cloud cover 51).
The month with the least cloud cover is August (Cloud cover 32).

Average visibility in May - Boston, MA
  • Average visibility in May: 9km

Months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (9km).
Months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (9km).