Boston
Massachusetts, USA
Long-term weather forecast
Long-term weather forecast

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 average temperature varying between 66.4°F (19.1°C) and 50°F (10°C).

Temperature

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

Humidity

The average relative humidity in May is 72%.

Rainfall

In May, in Boston, Massachusetts, 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

January through May, October through December are months with snowfall. May is the last month it regularly snows in Boston. During 0.1 snowfall days, 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 in May is 49.1°F (9.5°C).
Note: At temperatures below 50°F (10°C), swimming in a suitably protected swimsuit is feasible; otherwise, cold shock and loss of breathing control are imminent. Even a short swim, without thermal protection, at temperatures around 55.4°F (13°C) is not comfortable.

Daylight

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

Sunshine

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

UV index

In May, the average daily maximum UV index is 5. A UV Index of 3 to 5 symbolizes a medium vulnerability from the exposure to the Sun's UV rays for ordinary individuals.
Note: The average daily UV index of 5 transform into the following instructions:
Take precautions - Protection against the skin and eye damage is obliged. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects. 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, Massachusetts, 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, the average relative humidity in May is 72%.

How many days does it rain in May in Boston?

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 in Boston. During 0.1 snowfall days, in May, Boston aggregates 0.04" (1mm) of snow.

What is the water temperature in May in Boston?

In May, the average ocean temperature 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.

What is the average length of the day in May in Boston?

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

How long on average sun shines in May in Boston?

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

What is the UV index reading in May in Boston?

The average daily maximum UV index in May in Boston, Massachusetts, is 5. A UV Index of 3 to 5 symbolizes a medium hazard to health from the exposure to the Sun's UV radiation.
Average temperature in May - Boston, MA
  • Average high temperature in May: 66.4°F

The warmest month (with the highest average high temperature) is July (81.7°F).
The month with the lowest average high temperature is January (34.2°F).

  • Average low temperature in May: 50°F

The month with the highest average low temperature is July (64.9°F).
The coldest month (with the lowest average low temperature) is January (22.6°F).

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: 1.81"

Wettest months (with the highest rainfall) are March, April and December (2.91").
The driest month (with the lowest rainfall) is September (1.26").

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 lowest number of rainy days is January (7.9 days).

Average snowfall in May - Boston, MA
  • Average snowfall in May: 0.04"

The month with the highest snowfall is February (4.72").
Months with the lowest snowfall are June, July, August and September (0").

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 lowest number of snowfall days are June, July, August and September (0 days).

Average sea temperature in May - Boston, MA
  • Average sea temperature in May: 49.2°F

The best month for swimming (with the highest average sea temperature) is August (67.9°F).
The coldest month (with the lowest average sea temperature) is February (38.1°F).

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 shortest days is December (Average daylight: 9.1h).

  • Average sunshine in May: 8.3h

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

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).