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May Weather in Lewiston, United States

Last updated: June 24, 2025

In May, the average temperature in Lewiston, United States is a brisk 9°C (49°F), with nighttime lows dipping to a chilly -7°C (20°F) and daytime highs reaching a comfortable 28°C (82°F). Expect 66 mm (2.6 in) of precipitation over 13 days, contributing to an average humidity of 62%. Embrace the seasonal charm while preparing for a mix of weather!

May Temperature in Lewiston

In May in Lewiston, the average temperature is 9°C (49°F). Maximum temperatures can reach 28°C (82°F), while minimum temperatures can drop as low as -7°C (20°F). Be prepared for a wide range of temperatures when traveling during this month.

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

The chart illustrates May temperature patterns in Lewiston, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Lewiston, May typically has an average temperature of 9°C (49°F), with highs reaching up to 28°C (82°F) and lows dropping to around -7°C (20°F).
JanFebMarAprMayJunJulAugSepOctNovDec232534404962716959433323
Data source: Temperature data for Lewiston 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 Lewiston

In Lewiston in May, the total precipitation amount is 66 mm (2.6 in) spread over the course of 13 days.

May Precipitation Trends in Lewiston

The chart displays monthly precipitation patterns in Lewiston, 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 Lewiston, May typically receives around 66 mm (2.6 inches) of precipitation spread over approximately 13 days.
JanFebMarAprMayJunJulAugSepOctNovDec698963786631182336495659
Data source: Precipitation data for May generated using information from the Copernicus Climate Change Service.
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May Humidity in Lewiston

In Lewiston in May, humidity is 62%. With an average temperature of 9°C (49°F), this humidity feels like a brisk chill that can be invigorating for outdoor activities but may require a light jacket for comfort while traveling.

May Average Humidity in Lewiston

This chart illustrates the average monthly humidity levels in Lewiston, 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 Lewiston is approximately 62%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec91%92%84%75%62%56%44%37%46%67%84%88%
Data source: Humidity data for May generated using information from the Copernicus Climate Change Service.

May UV Index in Lewiston

In Lewiston 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 Lewiston.

Maximum UV Index Levels in Lewiston for May

The chart shows the monthly maximum UV Index (UVI) for Lewiston 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 Lewiston typically reaches 11, which falls under the extreme exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec35810111211119653
Data source: Lewiston 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 Lewiston Compares to Other Months

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

This table compares monthly weather conditions in Lewiston, showing how May’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-5°C (23°F)68 mm (2.7 inches)91%moderate
February Weather-4°C (25°F)89 mm (3.5 inches)92%moderate
March Weather1°C (34°F)63 mm (2.5 inches)84%very high
April Weather4°C (40°F)78 mm (3.1 inches)74%very high
May Weather9°C (49°F)66 mm (2.6 inches)62%extreme
June Weather17°C (62°F)31 mm (1.2 inches)56%extreme
July Weather22°C (71°F)17 mm (0.7 inches)44%extreme
August Weather20°C (69°F)23 mm (0.9 inches)37%extreme
September Weather15°C (59°F)36 mm (1.4 inches)46%very high
October Weather6°C (43°F)49 mm (1.9 inches)67%high
November Weather0°C (33°F)56 mm (2.2 inches)84%moderate
December Weather-5°C (23°F)59 mm (2.3 inches)88%moderate

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