May Weather in Washington, United States

Last updated: June 24, 2025

In May, the average temperature in Washington, United States hovers around 23°C (73°F), but temperatures can swing from a cool 7°C (45°F) to a scorching 37°C (98°F). Expect around 109 mm (4.3 in) of precipitation over 9 days, contributing to an average humidity level of 81%. Prepare for a month of varied weather!

May Temperature in Washington

In May in Washington, the average temperature is 23°C (73°F). The maximum can reach 37°C (98°F), while the minimum can drop to as low as 7°C (45°F). It's advisable to pack a range of clothing to comfortably enjoy your trip, as the weather can vary significantly throughout the day.

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

The chart illustrates May temperature patterns in Washington, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Washington, May typically has an average temperature of 23°C (73°F), with highs reaching up to 37°C (98°F) and lows dropping to around 7°C (45°F).

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

May Precipitation in Washington

In Washington in May, the total precipitation amount is 109 mm (4.3 in) spread over 9 days.

May Precipitation Trends in Washington

The chart displays monthly precipitation patterns in Washington, 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 Washington, May typically receives around 109 mm (4.3 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 Washington

In Washington in May, humidity is 81%. With an average temperature of 23°C (73°F), this humidity feels like a heavy blanket wrapping around you, making every step feel more laborious while traveling and causing you to constantly seek out shade or a cool breeze for relief.

May Average Humidity in Washington

This chart illustrates the average monthly humidity levels in Washington, 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 Washington is approximately 81%, 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 Washington

In Washington in May, the maximum UV index reaches 11, which corresponds to an extreme Exposure Category. With a time to burn of just 10 minutes, it's essential to take precautions. For more details, you can check the Hourly UV Index in Washington.

Maximum UV Index Levels in Washington for May

The chart shows the monthly maximum UV Index (UVI) for Washington 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 Washington typically reaches 11, which falls under the extreme exposure category.

Data source: Washington 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 Washington Compares to Other Months

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

This table compares monthly weather conditions in Washington, showing how May’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	9°C (48°F)	100 mm (3.9 inches)	86%	moderate
February Weather	12°C (53°F)	117 mm (4.6 inches)	84%	high
March Weather	14°C (58°F)	87 mm (3.4 inches)	83%	very high
April Weather	18°C (65°F)	107 mm (4.2 inches)	81%	very high
May Weather	23°C (73°F)	109 mm (4.3 inches)	81%	extreme
June Weather	26°C (79°F)	97 mm (3.8 inches)	81%	extreme
July Weather	27°C (82°F)	105 mm (4.1 inches)	83%	extreme
August Weather	27°C (81°F)	125 mm (4.9 inches)	81%	very high
September Weather	25°C (77°F)	98 mm (3.9 inches)	82%	very high
October Weather	20°C (68°F)	112 mm (4.4 inches)	78%	very high
November Weather	12°C (54°F)	82 mm (3.2 inches)	86%	high
December Weather	10°C (50°F)	117 mm (4.6 inches)	89%	moderate