May weather forecast
Boston, MA

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A beautiful natural park with the George Washington Monument in Boston, Massachusetts
A beautiful natural park with the George Washington Monument in Boston, Massachusetts

Weather in May

Boston in May is a delight for residents, offering pleasant climatic conditions. There's a shift from April’s delicate spring towards a warmer pre-summer atmosphere. Marked weather differences show that high and low temperatures range from 66.4°F (19.1°C) to 50°F (10°C). Most people enjoy the outdoor weather, with bustling patios and crowded city parks being the norm. When the Memorial Day Weekend kicks in, Bostonians officially consider it as the start of summer.

Temperature

The shift into May is characterized by a rise in the average high-temperature, transitioning from April's cool 55.2°F (12.9°C) to an enjoyable 66.4°F (19.1°C). In Boston, the expected average low-temperature for May is a cool 50°F (10°C).

Humidity

In Boston, the average relative humidity in May 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

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, in May, Boston aggregates 0.04" (1mm) of snow. In Boston, during the entire year, snow falls for 29.8 days and aggregates up to 15.75" (400mm) of snow.

Ocean temperature

In Boston, in May, the average water temperature is 49.1°F (9.5°C).
Note: You can swim in 49.1°F (9.5°C) below 50°F (10°C) with proper thermal wear; failing that, the cold shock and respiratory challenges are nearly certain. A short span at 55.4°F (13°C) without it is tough.

Daylight

In Boston, Massachusetts, the average length of the day in May is 14h and 37min.
On the first day of May in Boston, sunrise is at 5:38 am and sunset at 7:44 pm. On the last day of the month, sunrise is at 5:10 am and sunset at 8:14 pm EDT.

Sunshine

The average sunshine in May in Boston is 8.3h.

UV index

The average daily maximum UV index in May is 5. A UV Index estimate of 3 to 5 represents a moderate health risk from unsafe exposure to UV radiation for the average person.
Note: A maximum daily UV index of 5 during May morphs into the following directions:
Exercise prevention - Precautions against solar damage are endorsed. The Sun's UV radiation is especially harmful around midday, so reduce exposure and stay safe. A hat with a generous brim can prevent nearly 50% of UV rays from reaching your eyes. Guard yourself! Snow reflection can almost double the UV radiation from the Sun.
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Frequently asked questions

What is the usual temperature for Boston in May?

Boston in May has an average high-temperature of 66.4°F (19.1°C) and an average low-temperature of 50°F (10°C).

What is the average humidity in May in Boston?

In May, the average relative humidity is 72%.

How much does it rain in Boston in May?

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

How cold is the water in May in Boston?

In May, the average ocean temperature is 49.1°F (9.5°C). 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.

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

In Boston, Massachusetts, the average day length in May is 14h and 37min.

When is the sunrise / sunset in May in Boston?

On the first day of May in Boston, Massachusetts, sunrise is at 5:38 am and sunset at 7:44 pm. On the last day of the month, sunrise is at 5:10 am and sunset at 8:14 pm EDT.

How many hours of sunshine does Boston have in May?

In May, the average sunshine duration is 8.3h.

How high is the UV index in May in Boston?

In Boston, the average daily maximum UV index in May is 5. A UV Index reading of 3 to 5 represents a moderate vulnerability from unsafe exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in May
Boston, MA

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).

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Average pressure in May
Boston, MA

Average pressure in May - Boston, MA
  • Average pressure in May: 30.01"Hg

The month with the highest atmospheric pressure is November (30.06"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).

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Average wind speed in May
Boston, MA

Average wind speed in May - Boston, MA
  • Average wind speed in May: 7.4mph

The windiest month (with the highest average wind speed) is January (9.9mph).
The calmest month (with the lowest average wind speed) is August (6.2mph).

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Average humidity in May
Boston, MA

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%).

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Average rainfall in May
Boston, MA

Average rainfall in May - Boston, MA
  • Average rainfall in May: 1.81"

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

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Average rainfall days in May
Boston, MA

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).

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Average snowfall in May
Boston, MA

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

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

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Average snowfall days in May
Boston, MA

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

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

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Average sea temperature in May
Boston, MA

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).

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Average daylight in May /
Average sunshine in May
Boston, MA

Average daylight in May / Average sunshine in May - Boston, MA
  • Average daylight in May: 14h and 4min

The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 6min).

  • Average sunshine in May: 8h and 2min

The month with the most sunshine is August (Average sunshine: 10h and 30min).
The month with the least sunshine is February (Average sunshine: 4h and 36min).

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Average sunshine days in May
Boston, MA

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).

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Average UV index in May
Boston, MA

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

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

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Average cloud cover in May
Boston, MA

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).

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Average visibility in May
Boston, MA

Average visibility in May - Boston, MA
  • Average visibility in May: 6mi

The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

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Boston, Massachusetts, USA

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