August 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 August

Boston’s August weather is quite similar to July's, but with a slight decrease in temperature. Overall, a high temperature of 80.4°F (26.9°C) and a low of 64°F (17.8°C) becomes the new standard. Around this time, Boston experiences less humid conditions than those seen earlier in the summer. The vibrant city life followed by serene nights under the star-lit sky marks August as a memorable time. Summer's end has the city immersed in diverse cultural events and music festivals.

Temperature

Boston, Massachusetts, marks the start of August with an average high-temperature of a still moderately hot 80.4°F (26.9°C), hinting at a slight fluctuation from July's 81.7°F (27.6°C). Throughout the month of August, the nighttime temperature dips to an average of 64°F (17.8°C).

Humidity

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

Rainfall

In August, the rain falls for 11.7 days. Throughout August, 1.61" (41mm) of precipitation is accumulated. Throughout the year, in Boston, Massachusetts, there are 141.4 rainfall days, and 27.2" (691mm) of precipitation is accumulated.

Snowfall

June through September are months without snowfall.

Ocean temperature

With an average ocean temperature of 68°F (20°C), August is the month with the warmest seawater.
Note: For swimming, a surface water temperature of 68°F (20°C) is not enjoyable for the majority. It is not considered safe, as controlling breathing becomes progressively more difficult as water temperature decreases below 69.8°F (21°C).

Daylight

The average length of the day in August is 13h and 51min.
On the first day of the month, sunrise is at 5:37 am and sunset at 8:03 pm. On the last day of August, sunrise is at 6:09 am and sunset at 7:19 pm EDT.

Sunshine

The month with the most sunshine is August, with an average of 10.5h of sunshine.

UV index

The months with the highest UV index in Boston, Massachusetts, are June through August, with an average maximum UV index of 6. A UV Index of 6 to 7 symbolizes a high health vulnerability from exposure to the Sun's UV radiation for the average person.
Note: A maximum high UV index of 6 in August translates into the following recommendations:
Beware of overexposure. Fair-skinned individuals risk burning in less than 20 minutes. Seek shade and limit direct Sun exposure between 10 a.m. and 4 p.m., when UV radiation is at its peak, but be aware that not all shade structures provide complete sun protection. Arm yourself against UV rays' harm with protective apparel and UV-filtering shades.
Updated: Jun 21, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the average August temperature?

In Boston, in August, the average high-temperature is 80.4°F (26.9°C), and the average low-temperature is 64°F (17.8°C). The average heat index (a.k.a. 'apparent temperature', 'felt air temperature'), which calculates the temperature value influenced by the moisture in the air, in July is calculated to be 86°F (30°C).

What is the average humidity in August?

In August, the average relative humidity is 72%.

How many days does it rain in August?

In Boston, in August, it is raining for 11.7 days, with typically 1.61" (41mm) of accumulated precipitation.

When it does not snow?

In Boston, snow does not fall in June through September.

When is the ocean warmest?

The month with the warmest seawater is August, with an average ocean temperature of 68°F (20°C).

What is the ocean temperature in August?

In Boston, in August, the average water temperature is 68°F (20°C). For swimming, a surface water temperature of 68°F (20°C) is not enjoyable for the majority. It is not considered safe, as controlling breathing becomes progressively more difficult as water temperature decreases below 69.8°F (21°C).

How many hours of daylight does Boston have in August?

In Boston, the average day length in August is 13h and 51min.

What time are sunrise and sunset in August?

On the first day of August, sunrise is at 5:37 am and sunset at 8:03 pm. On the last day of the month, sunrise is at 6:09 am and sunset at 7:19 pm EDT.

What month has the most sunshine?

August has the most sunshine of the year in Boston, with an average of 10.5h of sunshine.

How long on average sun shines in August?

In Boston, the average sunshine duration in August is 10.5h.

What is the month with the highest UV index?

The months with the highest UV index in Boston are June through August, with an average maximum UV index of 6.

What is the UV index intensity in August?

In Boston, Massachusetts, the average daily maximum UV index in August is 6. A UV Index estimate of 6 to 7 represents a high health risk from exposure to Sun's UV rays.
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 August
Boston, MA

Average temperature in August - Boston, MA
  • Average high temperature in August: 80.4°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 August: 64°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 pressure in August
Boston, MA

Average pressure in August - Boston, MA
  • Average pressure in August: 29.98"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).

Average wind speed in August
Boston, MA

Average wind speed in August - Boston, MA
  • Average wind speed in August: 6.2mph

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).

Average humidity in August
Boston, MA

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

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

Average rainfall in August
Boston, MA

Average rainfall in August - Boston, MA
  • Average rainfall in August: 1.61"

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").

Average rainfall days in August
Boston, MA

Average rainfall days in August - Boston, MA
  • Average rainfall days in August: 11.7 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 August
Boston, MA

Average snowfall in August - Boston, MA
  • Average snowfall in August: 0"

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

Average snowfall days in August
Boston, MA

Average snowfall days in August - Boston, MA
  • Average snowfall days in August: 0 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).

Average sea temperature in August
Boston, MA

Average sea temperature in August - Boston, MA
  • Average sea temperature in August: 67.9°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 August /
Average sunshine in August
Boston, MA

Average daylight in August / Average sunshine in August - Boston, MA
  • Average daylight in August: 13h and 5min

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 August: 10h and 3min

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).

Average sunshine days in August
Boston, MA

Average sunshine days in August - Boston, MA
  • Average sunshine days in August: 17 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 August
Boston, MA

Average UV index in August - Boston, MA
  • Average UV index in August: 6

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).

Average cloud cover in August
Boston, MA

Average cloud cover in August - Boston, MA
  • Average cloud cover in August: 32

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 August
Boston, MA

Average visibility in August - Boston, MA
  • Average visibility in August: 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).

Boston, Massachusetts, USA

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