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September Weather in Joint Base Lewis McChord, United States

Last updated: June 24, 2025

In Joint Base Lewis McChord, United States, the average temperature in September is a comfortable 16°C (60°F). Expect minimums of 6°C (42°F) and maximums reaching up to 30°C (85°F). During this month, you might experience 90 mm (3.5 in) of precipitation over about 10 days, accompanied by an average humidity level of 74%.

September Temperature in Joint Base Lewis McChord

In September in Joint Base Lewis McChord, the average temperature is 16°C (60°F), with maximums reaching 30°C (85°F) and minimums dropping as low as 6°C (42°F). This variation makes it a great time to explore, as you can enjoy mild days and cooler evenings.

September Weather in Joint Base Lewis McChord: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Joint Base Lewis McChord, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Joint Base Lewis McChord, September typically has an average temperature of 16°C (60°F), with highs reaching up to 30°C (85°F) and lows dropping to around 6°C (42°F).
JanFebMarAprMayJunJulAugSepOctNovDec413944495560656560504541
Data source: Temperature data for Joint Base Lewis McChord 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.

September Precipitation in Joint Base Lewis McChord

In Joint Base Lewis McChord in September, the precipitation amount is 90 mm (3.5 in) over the course of 10 days.

September Precipitation Trends in Joint Base Lewis McChord

The chart displays monthly precipitation patterns in Joint Base Lewis McChord, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Joint Base Lewis McChord, September typically receives around 90 mm (3.5 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec1831891361186858111390142180201
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Joint Base Lewis McChord

In Joint Base Lewis McChord in September humidity is 74%. With an average temperature of 16°C (60°F), this humidity feels like a damp blanket enveloping you, making traveling a bit uncomfortable as you navigate the sticky air and potentially limiting your energy for exploring the sights.

September Average Humidity in Joint Base Lewis McChord

This chart illustrates the average monthly humidity levels in Joint Base Lewis McChord, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Joint Base Lewis McChord is approximately 74%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec86%84%85%83%84%84%82%73%74%83%86%87%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Joint Base Lewis McChord

In Joint Base Lewis McChord in September, the maximum UV index is 7, which corresponds to the high Exposure Category. This means that the time to burn is approximately 25 minutes. For more detailed information, you can check the Hourly UV Index in Joint Base Lewis McChord.

Maximum UV Index Levels in Joint Base Lewis McChord for September

The chart shows the monthly maximum UV Index (UVI) for Joint Base Lewis McChord in September, 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 September, the maximum UV index in Joint Base Lewis McChord typically reaches 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec235689987532
Data source: Joint Base Lewis McChord September 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 September Weather in Joint Base Lewis McChord Compares to Other Months

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

This table compares monthly weather conditions in Joint Base Lewis McChord, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather5°C (41°F)183 mm (7.2 inches)86%low
February Weather4°C (40°F)189 mm (7.4 inches)84%moderate
March Weather7°C (44°F)136 mm (5.4 inches)85%moderate
April Weather9°C (49°F)118 mm (4.7 inches)83%high
May Weather13°C (55°F)68 mm (2.7 inches)84%very high
June Weather16°C (60°F)58 mm (2.3 inches)84%very high
July Weather18°C (65°F)11 mm (0.4 inches)82%very high
August Weather18°C (66°F)13 mm (0.5 inches)73%very high
September Weather16°C (60°F)90 mm (3.5 inches)74%high
October Weather10°C (51°F)142 mm (5.6 inches)83%moderate
November Weather7°C (45°F)180 mm (7.1 inches)86%moderate
December Weather5°C (41°F)201 mm (7.9 inches)87%low

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