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September Weather in Richland, United States

Last updated: June 24, 2025

In September, the average temperature in Richland, United States hovers around 17°C (63°F), with minimums dipping to 2°C (36°F) and maximums reaching 31°C (89°F). Expect about 98 mm (3.9 in) of precipitation spread over 9 days, accompanied by an average humidity of 78%.

September Temperature in Richland

In September in Richland, the average temperature is 17°C (63°F). Maximum temperatures can reach 31°C (89°F), while minimums can drop as low as 2°C (36°F). Be prepared for a range of temperatures, making it a perfect time for both outdoor adventures and cozy indoor activities.

September Weather in Richland: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Richland, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Richland, September typically has an average temperature of 17°C (63°F), with highs reaching up to 31°C (89°F) and lows dropping to around 2°C (36°F).
JanFebMarAprMayJunJulAugSepOctNovDec232632445766717063523829
Data source: Temperature data for Richland 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 Richland

In Richland in September, the precipitation amount is 98 mm (3.9 in) spread over a duration of 9 days.

September Precipitation Trends in Richland

The chart displays monthly precipitation patterns in Richland, 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 Richland, September typically receives around 98 mm (3.9 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec11612010614113411218412398190139142
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Richland

In Richland in September, humidity is 78%. With an average temperature of 17°C (63°F), this humidity feels like a warm, enveloping blanket, making traveling slightly uncomfortable as you navigate the sticky air, prompting the need for frequent breaks in cooler, shaded areas.

September Average Humidity in Richland

This chart illustrates the average monthly humidity levels in Richland, 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 Richland is approximately 78%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec90%90%87%88%82%79%78%76%78%84%89%86%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Richland

In Richland 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 Richland.

Maximum UV Index Levels in Richland for September

The chart shows the monthly maximum UV Index (UVI) for Richland 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 Richland typically reaches 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3468910997532
Data source: Richland 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 Richland Compares to Other Months

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

This table compares monthly weather conditions in Richland, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-5°C (24°F)116 mm (4.6 inches)90%moderate
February Weather-3°C (26°F)119 mm (4.7 inches)90%moderate
March Weather0°C (33°F)106 mm (4.2 inches)87%high
April Weather7°C (45°F)141 mm (5.6 inches)88%very high
May Weather14°C (57°F)134 mm (5.3 inches)82%very high
June Weather19°C (66°F)112 mm (4.4 inches)79%very high
July Weather22°C (72°F)184 mm (7.2 inches)78%very high
August Weather21°C (70°F)123 mm (4.8 inches)76%very high
September Weather17°C (63°F)98 mm (3.9 inches)78%high
October Weather11°C (53°F)190 mm (7.5 inches)84%moderate
November Weather3°C (38°F)139 mm (5.5 inches)89%moderate
December Weather-1°C (30°F)142 mm (5.6 inches)86%low

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