May Weather in Washington, United States

Last updated: June 24, 2025

In Washington, United States, the average temperature for May hovers around 18°C (65°F), with temperatures ranging from a chilly 0°C (32°F) to a sizzling 33°C (92°F). Expect about 125 mm (4.9 in) of precipitation spread over 13 days, contributing to an average humidity level of 78%. Perfect for those who enjoy a touch of variation in their climate!

May Temperature in Washington

In May in Washington, the average temperature is 18°C (65°F). Maximums can reach 33°C (92°F), and minimums can be as low as 0°C (32°F). This variability makes Washington an interesting destination for travelers looking to experience a range of temperatures.

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 18°C (65°F), with highs reaching up to 33°C (92°F) and lows dropping to around 0°C (32°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 125 mm (4.9 in), occurring over a span of 13 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 125 mm (4.9 inches) of precipitation spread over approximately 13 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 78%. With an average temperature of 18°C (65°F), this humidity feels like a warm, enveloping blanket, making travel quite muggy and potentially uncomfortable, as it can leave you feeling sticky and fatigued more quickly than usual.

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 78%, 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	1°C (35°F)	59 mm (2.3 inches)	86%	moderate
February Weather	4°C (40°F)	90 mm (3.6 inches)	86%	moderate
March Weather	7°C (45°F)	76 mm (3.0 inches)	86%	high
April Weather	13°C (55°F)	105 mm (4.1 inches)	84%	very high
May Weather	18°C (65°F)	125 mm (4.9 inches)	78%	extreme
June Weather	22°C (73°F)	121 mm (4.8 inches)	79%	very high
July Weather	25°C (78°F)	103 mm (4.1 inches)	70%	very high
August Weather	24°C (75°F)	132 mm (5.2 inches)	59%	very high
September Weather	21°C (69°F)	108 mm (4.3 inches)	68%	very high
October Weather	15°C (60°F)	103 mm (4.1 inches)	80%	high
November Weather	7°C (45°F)	83 mm (3.3 inches)	86%	moderate
December Weather	4°C (39°F)	85 mm (3.4 inches)	85%	moderate