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May Weather in Issaquah, United States

Last updated: June 24, 2025

In Issaquah, United States, the average temperature in May hovers around 13°C (55°F), with fluctuations ranging from a cool 1°C (35°F) to a warm 30°C (86°F). Expect about 85 mm (3.3 in) of precipitation over 14 days, contributing to an average humidity level of 81%. Stay prepared for a mix of weather as you embrace this vibrant month!

May Temperature in Issaquah

In May in Issaquah, the average temperature is 13°C (55°F). The maximum can reach 30°C (86°F), and the minimum can be as low as 1°C (35°F). Be prepared for a range of temperatures to ensure a comfortable trip.

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

The chart illustrates May temperature patterns in Issaquah, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Issaquah, May typically has an average temperature of 13°C (55°F), with highs reaching up to 30°C (86°F) and lows dropping to around 1°C (35°F).
JanFebMarAprMayJunJulAugSepOctNovDec403844495560656560504540
Data source: Temperature data for Issaquah 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 Issaquah

In Issaquah in May, the precipitation amount is 85 mm (3.3 in) over the course of 14 days.

May Precipitation Trends in Issaquah

The chart displays monthly precipitation patterns in Issaquah, 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 Issaquah, May typically receives around 85 mm (3.3 inches) of precipitation spread over approximately 14 days.
JanFebMarAprMayJunJulAugSepOctNovDec20023415214485782823115205217235
Data source: Precipitation data for May generated using information from the Copernicus Climate Change Service.
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May Humidity in Issaquah

In Issaquah in May, humidity is 81%. With an average temperature of 13°C (55°F), this humidity feels like a damp blanket wrapping around you, making strolls outdoors feel heavy and slightly oppressive, which may be less than ideal for travelers looking to explore comfortably.

May Average Humidity in Issaquah

This chart illustrates the average monthly humidity levels in Issaquah, 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 Issaquah is approximately 81%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec86%86%87%84%81%82%79%63%62%83%89%88%
Data source: Humidity data for May generated using information from the Copernicus Climate Change Service.

May UV Index in Issaquah

In Issaquah in May, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in Issaquah.

Maximum UV Index Levels in Issaquah for May

The chart shows the monthly maximum UV Index (UVI) for Issaquah 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 Issaquah typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec235689987522
Data source: Issaquah 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 Issaquah Compares to Other Months

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

This table compares monthly weather conditions in Issaquah, showing how May’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather5°C (40°F)199 mm (7.9 inches)86%low
February Weather4°C (39°F)234 mm (9.2 inches)86%moderate
March Weather7°C (44°F)152 mm (6.0 inches)87%moderate
April Weather9°C (49°F)144 mm (5.7 inches)84%high
May Weather13°C (55°F)85 mm (3.3 inches)81%very high
June Weather16°C (60°F)78 mm (3.1 inches)82%very high
July Weather18°C (65°F)28 mm (1.1 inches)79%very high
August Weather18°C (65°F)23 mm (0.9 inches)63%very high
September Weather15°C (60°F)115 mm (4.5 inches)62%high
October Weather10°C (50°F)204 mm (8.1 inches)83%moderate
November Weather7°C (45°F)217 mm (8.5 inches)89%low
December Weather4°C (40°F)235 mm (9.3 inches)88%low

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