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May Weather in Washington, United States

Last updated: June 24, 2025

In Washington, United States, the average temperature in May hovers around 20°C (67°F). However, you can expect a range that dips to a chilly 1°C (34°F) and peaks at a warm 34°C (94°F). With 133 mm (5.2 in) of precipitation spread over 14 days, it's wise to keep an umbrella handy. The humidity level is notable at 79%, adding a touch of mugginess to the air.

May Temperature in Washington

In May in Washington, the average temperature is 20°C (67°F). The maximum can reach up to 34°C (94°F) and the minimum can be as low as 1°C (34°F). It's advisable to pack layers to stay comfortable while exploring the diverse weather conditions.

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 20°C (67°F), with highs reaching up to 34°C (94°F) and lows dropping to around 1°C (34°F).
JanFebMarAprMayJunJulAugSepOctNovDec333746556776797672604439
Data source: Temperature data for Washington generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

May Precipitation in Washington

In Washington in May, the precipitation amount is 133 mm (5.2 in) occurring over the course of 14 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 133 mm (5.2 inches) of precipitation spread over approximately 14 days.
JanFebMarAprMayJunJulAugSepOctNovDec9411413912313311889917197102104
Data source: Precipitation data for May generated using information from the Copernicus Climate Change Service.
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May Humidity in Washington

In Washington in May, humidity is 79%. With an average temperature of 20°C (67°F), this humidity feels like a warm, heavy blanket wrapping around you, making traveling a bit sluggish and requiring frequent breaks to stay refreshed.

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 79%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec87%85%86%84%79%82%79%70%69%76%88%87%
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 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 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 10, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec357910111098643
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.
 TemperaturePrecipitationHumidityUV
January Weather1°C (33°F)93 mm (3.7 inches)87%moderate
February Weather3°C (37°F)114 mm (4.5 inches)85%moderate
March Weather8°C (47°F)139 mm (5.5 inches)86%high
April Weather13°C (55°F)123 mm (4.8 inches)84%very high
May Weather20°C (67°F)133 mm (5.2 inches)79%very high
June Weather24°C (76°F)118 mm (4.6 inches)82%extreme
July Weather26°C (79°F)89 mm (3.5 inches)79%very high
August Weather24°C (76°F)91 mm (3.6 inches)70%very high
September Weather22°C (72°F)71 mm (2.8 inches)69%very high
October Weather16°C (60°F)97 mm (3.8 inches)76%high
November Weather7°C (44°F)102 mm (4.0 inches)88%moderate
December Weather4°C (39°F)104 mm (4.1 inches)87%moderate

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