May Weather in Boston, United States

Last updated: June 24, 2025

In May, the average temperature in Boston, United States hovers around 17°C (64°F), with a comfortable range that sees minimums of 6°C (44°F) and maximums reaching 27°C (80°F). Expect to experience about 89 mm (3.5 in) of precipitation over 9 days, contributing to a relatively high average humidity of 80%. Be prepared for both the warmth and the occasional drizzle during your stay!

May Temperature in Boston

In May in Boston, the average temperature is 17°C (64°F). The maximum can reach 27°C (80°F), while the minimum can dip as low as 6°C (44°F). This mild climate makes it an ideal destination for outdoor activities and sightseeing.

May Weather in Boston: Daily Temperature Highs, Lows, and Averages

The chart illustrates May temperature patterns in Boston, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Boston, May typically has an average temperature of 17°C (64°F), with highs reaching up to 27°C (80°F) and lows dropping to around 6°C (44°F).

Data source: Temperature data for Boston generated using information from the Copernicus Climate Change Service.

May Precipitation in Boston

In Boston in May, the precipitation amount is 89 mm (3.5 in) during a span of 9 days.

May Precipitation Trends in Boston

The chart displays monthly precipitation patterns in Boston, with values for each month alongside May’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how May’s conditions compare to those of other months. In Boston, May typically receives around 89 mm (3.5 inches) of precipitation spread over approximately 9 days.

Data source: Precipitation data for May generated using information from the Copernicus Climate Change Service.

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Millimeters (mm) Inches (in)

May Humidity in Boston

In Boston in May, humidity is 80%. With an average temperature of 17°C (64°F), this humidity feels like a warm blanket wrapping around you, making travel somewhat uncomfortable as the air feels heavy and oppressive.

May Average Humidity in Boston

This chart illustrates the average monthly humidity levels in Boston, with May’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In May, average humidity in Boston is approximately 80%, offering insight into how humid the weather typically is during this month.

Data source: Humidity data for May generated using information from the Copernicus Climate Change Service.

May UV Index in Boston

In Boston in May, the maximum UV index reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more detailed information, you can check the Hourly UV Index in Boston.

Maximum UV Index Levels in Boston for May

The chart shows the monthly maximum UV Index (UVI) for Boston in May, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In May, the maximum UV index in Boston typically reaches 10, which falls under the very high exposure category.

Data source: Boston May UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

Extreme (11+): Avoid the sun, stay in shade.
Very High (8-10): Limit sun exposure.
High (6-7): Use SPF 30+ and protective clothing.
Moderate (3-5): Midday shade recommended.
Low (0-2): No protection needed.

How May Weather in Boston Compares to Other Months

Weather in Boston varies notably across the year, with each month offering distinct climate conditions. This page compares May’s weather to other months in Boston, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Boston, showing how May’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	5°C (41°F)	94 mm (3.7 inches)	84%	moderate
February Weather	6°C (43°F)	119 mm (4.7 inches)	83%	moderate
March Weather	8°C (47°F)	87 mm (3.4 inches)	82%	high
April Weather	13°C (55°F)	86 mm (3.4 inches)	81%	very high
May Weather	17°C (64°F)	89 mm (3.5 inches)	80%	very high
June Weather	23°C (73°F)	73 mm (2.9 inches)	82%	very high
July Weather	26°C (79°F)	107 mm (4.2 inches)	81%	extreme
August Weather	26°C (78°F)	104 mm (4.1 inches)	81%	very high
September Weather	23°C (75°F)	105 mm (4.1 inches)	78%	very high
October Weather	19°C (67°F)	108 mm (4.2 inches)	80%	high
November Weather	12°C (54°F)	91 mm (3.6 inches)	84%	moderate
December Weather	8°C (47°F)	102 mm (4.0 inches)	84%	moderate