May Weather in Waltham, United States

Last updated: June 24, 2025

In Waltham, United States, the average temperature in May hovers around 15°C (59°F). Expect a range where the minimum can dip to 2°C (36°F) and the maximum may soar to 35°C (95°F). With a precipitation amount of 86 mm (3.4 in) spread over 11 days, the month also boasts an average humidity level of 72%. Prepare for a mix of weather conditions!

May Temperature in Waltham

In May in Waltham, the average temperature is 15°C (59°F). Maximum temperatures can reach 35°C (95°F), while the minimum can drop to as low as 2°C (36°F). Be prepared for a range of weather conditions when traveling during this time.

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

The chart illustrates May temperature patterns in Waltham, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Waltham, May typically has an average temperature of 15°C (59°F), with highs reaching up to 35°C (95°F) and lows dropping to around 2°C (36°F).

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

May Precipitation in Waltham

In Waltham in May, the precipitation amount is 86 mm (3.4 in), spread over 11 days.

May Precipitation Trends in Waltham

The chart displays monthly precipitation patterns in Waltham, 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 Waltham, May typically receives around 86 mm (3.4 inches) of precipitation spread over approximately 11 days.

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

Choose your preferred precipitation unit

Millimeters (mm) Inches (in)

May Humidity in Waltham

In Waltham in May humidity is 72%. With an average temperature of 15°C (59°F), this humidity feels like a warm blanket wrapping around you, creating a sultry atmosphere that can make traveling a bit uncomfortable. The stickiness in the air can leave you feeling sluggish, so it’s advisable to stay hydrated and take breaks often while exploring.

May Average Humidity in Waltham

This chart illustrates the average monthly humidity levels in Waltham, 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 Waltham is approximately 72%, 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 Waltham

In Waltham in May, the maximum UV index is 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check the Hourly UV Index in Waltham.

Maximum UV Index Levels in Waltham for May

The chart shows the monthly maximum UV Index (UVI) for Waltham 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 Waltham typically reaches 9, which falls under the very high exposure category.

Data source: Waltham 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 Waltham Compares to Other Months

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

This table compares monthly weather conditions in Waltham, showing how May’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	-1°C (31°F)	71 mm (2.8 inches)	86%	moderate
February Weather	0°C (33°F)	87 mm (3.4 inches)	84%	moderate
March Weather	3°C (38°F)	89 mm (3.5 inches)	82%	moderate
April Weather	9°C (48°F)	127 mm (5.0 inches)	80%	very high
May Weather	15°C (59°F)	86 mm (3.4 inches)	72%	very high
June Weather	20°C (69°F)	85 mm (3.4 inches)	72%	very high
July Weather	23°C (74°F)	125 mm (4.9 inches)	67%	very high
August Weather	23°C (74°F)	79 mm (3.1 inches)	66%	very high
September Weather	19°C (67°F)	79 mm (3.1 inches)	71%	high
October Weather	13°C (56°F)	132 mm (5.2 inches)	78%	high
November Weather	6°C (43°F)	95 mm (3.7 inches)	84%	moderate
December Weather	1°C (34°F)	119 mm (4.7 inches)	81%	low