September Weather in Richland, United States

Last updated: June 24, 2025

In Richland, United States, the average temperature in September hovers around 20°C (69°F). Expect a range with minimums dipping to 5°C (42°F) and maximums soaring up to 34°C (93°F). During this time, precipitation averages 121 mm (4.8 in) spread over 8 days, contributing to an average humidity level of 78%. Perfect for those who enjoy a touch of warmth with a hint of moisture in the air!

September Temperature in Richland

In September in Richland, the average temperature is 20°C (69°F). Maximum temperatures can reach 34°C (93°F), while minimums can drop as low as 5°C (42°F). This makes it a great time to explore outdoor attractions, but travelers should be prepared for both warm and cool weather.

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 20°C (69°F), with highs reaching up to 34°C (93°F) and lows dropping to around 5°C (42°F).

Data source: Temperature data for Richland generated using information from the Copernicus Climate Change Service.

September Precipitation in Richland

In Richland in September, the precipitation amount is 121 mm (4.8 in) over the course of 8 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 121 mm (4.8 inches) of precipitation spread over approximately 8 days.

Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.

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Millimeters (mm) Inches (in)

September Humidity in Richland

In Richland in September, humidity is 78%. With an average temperature of 20°C (69°F), this humidity feels like a warm, enveloping blanket, making travel somewhat uncomfortable as sweat clings to your skin and the air feels thick and heavy, urging you to seek out shaded areas and refreshing drinks.

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.

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 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 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 8, which falls under the very high exposure category.

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.
	Temperature	Precipitation	Humidity	UV
January Weather	-5°C (24°F)	50 mm (2.0 inches)	81%	moderate
February Weather	-4°C (26°F)	56 mm (2.2 inches)	81%	moderate
March Weather	5°C (41°F)	87 mm (3.4 inches)	81%	high
April Weather	10°C (50°F)	81 mm (3.2 inches)	82%	very high
May Weather	17°C (63°F)	151 mm (5.9 inches)	78%	very high
June Weather	24°C (75°F)	137 mm (5.4 inches)	81%	extreme
July Weather	25°C (77°F)	70 mm (2.8 inches)	79%	very high
August Weather	23°C (74°F)	70 mm (2.8 inches)	77%	very high
September Weather	20°C (69°F)	121 mm (4.8 inches)	78%	very high
October Weather	12°C (54°F)	126 mm (5.0 inches)	78%	high
November Weather	4°C (39°F)	52 mm (2.1 inches)	87%	moderate
December Weather	0°C (32°F)	45 mm (1.8 inches)	84%	moderate