September Weather in Cool, United States

Last updated: June 24, 2025

In September, the average temperature in Cool, United States reaches a comfortable 23°C (73°F). However, be prepared for a possible range, with minimums dipping to 7°C (45°F) and maximums soaring up to 42°C (108°F). Expect a slight chance of rain, with an average precipitation of 17 mm (0.7 in) spread over just 2 days. On top of that, you'll enjoy a relatively dry environment, with an average humidity of only 44%.

September Temperature in Cool

In September in Cool, the average temperature is 23°C (73°F). Maximum temperatures can reach up to 42°C (108°F), while minimum temperatures can dip as low as 7°C (45°F). This variation in temperatures suggests that travelers should be prepared for both warm days and cooler nights.

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

The chart illustrates September temperature patterns in Cool, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Cool, September typically has an average temperature of 23°C (73°F), with highs reaching up to 42°C (108°F) and lows dropping to around 7°C (45°F).

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

September Precipitation in Cool

In Cool in September, the precipitation amount is 17 mm (0.7 in) over a span of 2 days.

September Precipitation Trends in Cool

The chart displays monthly precipitation patterns in Cool, 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 Cool, September typically receives around 17 mm (0.7 inches) of precipitation spread over approximately 2 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 Cool

In Cool in September humidity is 44%. With an average temperature of 23°C (73°F), this humidity feels like a pleasant embrace, making it comfortable for travelers to explore and enjoy outdoor activities without feeling too sticky or overheated.

September Average Humidity in Cool

This chart illustrates the average monthly humidity levels in Cool, 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 Cool is approximately 44%, 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 Cool

In Cool in September, the maximum UV index is 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check the Hourly UV Index in Cool.

Maximum UV Index Levels in Cool for September

The chart shows the monthly maximum UV Index (UVI) for Cool 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 Cool typically reaches 9, which falls under the very high exposure category.

Data source: Cool 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 Cool Compares to Other Months

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

This table compares monthly weather conditions in Cool, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	8°C (47°F)	227 mm (8.9 inches)	84%	moderate
February Weather	9°C (49°F)	230 mm (9.1 inches)	84%	moderate
March Weather	11°C (52°F)	237 mm (9.3 inches)	83%	high
April Weather	14°C (58°F)	112 mm (4.4 inches)	81%	very high
May Weather	18°C (65°F)	62 mm (2.4 inches)	74%	very high
June Weather	23°C (74°F)	8 mm (0.3 inches)	64%	extreme
July Weather	27°C (80°F)	0 mm (0.0 inches)	44%	extreme
August Weather	26°C (79°F)	0 mm (0.0 inches)	36%	very high
September Weather	23°C (73°F)	17 mm (0.7 inches)	44%	very high
October Weather	17°C (63°F)	67 mm (2.7 inches)	65%	high
November Weather	11°C (53°F)	131 mm (5.1 inches)	84%	moderate
December Weather	8°C (47°F)	178 mm (7.0 inches)	83%	moderate