May weather forecast
Waltham, MA

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Weather in May

May is known for mild weather in Waltham, Massachusetts, with a balance between pleasant temperatures and consistent precipitation. Temperature fluctuations stabilize, and rainfall serves as an essential element to enhance the vegatation, producing a green panorama. The average temperatures hit peaks of 66.9°F (19.4°C) and take lows down to 49.6°F (9.8°C). As the city bathes in the longer daylight periods, the weather creates an overall appealing scenario with a perfect blend of warmth and moisture.

Temperature

Waltham experiences a temperature shift with the start of May, with average high-temperatures moving from a mild 55.9°F (13.3°C) in April to a still refreshing 66.9°F (19.4°C). Waltham observes an average low-temperature of 49.6°F (9.8°C) during May nights.

Humidity

In May, the average relative humidity in Waltham is 73%.

Rainfall

In Waltham, Massachusetts, in May, during 10.6 rainfall days, 0.75" (19mm) of precipitation is typically accumulated. In Waltham, Massachusetts, during the entire year, the rain falls for 106.3 days and collects up to 8.5" (216mm) of precipitation.

Snowfall

Months with snowfall are January through May, November and December. May is the last month it regularly snows in Waltham. During 0.1 snowfall days, in May, Waltham aggregates 0.04" (1mm) of snow. Throughout the year, in Waltham, Massachusetts, there are 19.6 snowfall days, and 4.02" (102mm) of snow is accumulated.

Daylight

In Waltham, the average length of the day in May is 14h and 37min.
On the first day of May in Waltham, sunrise is at 5:38 am and sunset at 7:45 pm. On the last day of the month, sunrise is at 5:10 am and sunset at 8:14 pm EDT.

Sunshine

In May, the average sunshine is 8.4h.

UV index

In May, the average daily maximum UV index is 5. A UV Index reading of 3 to 5 represents a moderate threat to health from unprotected exposure to Sun's UV rays for the ordinary person.
Note: The maximum daily UV index, 5 in May, converts into the following recommendations:
Be vigilant - A duty to shield skin and eyes from injury exists. Direct Sun exposure should be minimized especially during midday when radiation is most intense. A hat with a generous brim can prevent nearly 50% of UV rays from reaching your eyes. Be cautious! The UV radiation from the Sun can be magnified almost twofold by snow reflection.
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Frequently asked questions

What is the average May temperature in Waltham?

In Waltham, 66.9°F (19.4°C) is the average high-temperature and 49.6°F (9.8°C) is the average low-temperature during May.

What is the average humidity in May in Waltham?

In Waltham, Massachusetts, the average relative humidity in May is 73%.

How much does it rain in Waltham in May?

In Waltham, Massachusetts, in May, it is raining for 10.6 days, with typically 0.75" (19mm) of accumulated precipitation.

What is the last month it snows in Waltham?

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

How many hours of daylight does Waltham have in May?

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

When are sunrise and sunset in May in Waltham?

In May, on the first day of the month, sunrise is at 5:38 am and sunset at 7:45 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 Waltham have in May?

In Waltham, Massachusetts, the average sunshine duration in May is 8.4h.

What is the UV index reading in May in Waltham?

The average daily maximum UV index in May is 5. A UV Index value of 3 to 5 symbolizes a medium health risk from exposure to the Sun's UV radiation.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in May
Waltham, MA

Average temperature in May - Waltham, MA
  • Average high temperature in May: 66.9°F

The warmest month (with the highest average high temperature) is July (82°F).
The month with the lowest average high temperature is January (33.3°F).

  • Average low temperature in May: 49.6°F

The month with the highest average low temperature is July (64°F).
The coldest month (with the lowest average low temperature) is January (21.6°F).

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Average pressure in May
Waltham, MA

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

The month with the highest atmospheric pressure is November (30.07"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).

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Average wind speed in May
Waltham, MA

Average wind speed in May - Waltham, MA
  • Average wind speed in May: 7mph

The windiest month (with the highest average wind speed) is January (9.1mph).
The calmest month (with the lowest average wind speed) is August (5.8mph).

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Average humidity in May
Waltham, MA

Average humidity in May - Waltham, MA
  • Average humidity in May: 73%

The month with the highest relative humidity is February (78%).
The month with the lowest relative humidity is April (70%).

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Average rainfall in May
Waltham, MA

Average rainfall in May - Waltham, MA
  • Average rainfall in May: 0.75"

The wettest months (with the highest rainfall) are April and November (0.87").
The driest month (with the least rainfall) is September (0.35").

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Average rainfall days in May
Waltham, MA

Average rainfall days in May - Waltham, MA
  • Average rainfall days in May: 10.6 days

The month with the highest number of rainy days is July (12.4 days).
The month with the least rainy days is January (5.3 days).

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Average snowfall in May
Waltham, MA

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

The month with the highest snowfall is December (1.14").
The months with the least snowfall are June, July, August, September and October (0").

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Average snowfall days in May
Waltham, MA

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

The month with the highest number of snowfall days is February (5.4 days).
The months with the least snowfall days are June, July, August, September and October (0 days).

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

Average daylight in May / Average sunshine in May - Waltham, 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 42min).

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Average sunshine days in May
Waltham, MA

Average sunshine days in May - Waltham, MA
  • Average sunshine days in May: 17 days

The month with the most sunshine days is January (22.2 days).
The month with the least sunshine days is June (15.8 days).

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Average UV index in May
Waltham, MA

Average UV index in May - Waltham, 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
Waltham, MA

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

The month with the most cloud cover is March (Cloud cover 50).
The month with the least cloud cover is August (Cloud cover 32).

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Average visibility in May
Waltham, MA

Average visibility in May - Waltham, 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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Waltham, Massachusetts, USA

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