September Weather in Greeley, United States

Last updated: June 24, 2025

The average temperature in Greeley, United States for September is a pleasant 20°C (68°F), with fluctuations that can bring lows of 1°C (34°F) and highs reaching up to 38°C (100°F). During this month, expect a precipitation amount of about 15 mm (0.6 in) spread over 3 days, while the average humidity sits comfortably at 75%. Enjoy the varied weather this month has to offer!

September Temperature in Greeley

In September in Greeley, the average temperature is 20°C (68°F). Maximums can reach 38°C (100°F) and minimums can be as low as 1°C (34°F). Be prepared for a wide range of temperatures during your travels, so pack accordingly!

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

The chart illustrates September temperature patterns in Greeley, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Greeley, September typically has an average temperature of 20°C (68°F), with highs reaching up to 38°C (100°F) and lows dropping to around 1°C (34°F).

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

September Precipitation in Greeley

In Greeley in September, the precipitation amount is 15 mm (0.6 in) over the course of 3 days.

September Precipitation Trends in Greeley

The chart displays monthly precipitation patterns in Greeley, 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 Greeley, September typically receives around 15 mm (0.6 inches) of precipitation spread over approximately 3 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 Greeley

In Greeley in September, humidity is 75%. With an average temperature of 20°C (68°F), this humidity feels like a warm, muggy embrace that can leave travelers feeling sticky and exhausted.

September Average Humidity in Greeley

This chart illustrates the average monthly humidity levels in Greeley, 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 Greeley is approximately 75%, 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 Greeley

In Greeley 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 Greeley.

Maximum UV Index Levels in Greeley for September

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

Data source: Greeley 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 Greeley Compares to Other Months

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

This table compares monthly weather conditions in Greeley, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	-1°C (31°F)	11 mm (0.4 inches)	72%	moderate
February Weather	-1°C (30°F)	13 mm (0.5 inches)	76%	moderate
March Weather	5°C (42°F)	44 mm (1.7 inches)	61%	high
April Weather	9°C (49°F)	35 mm (1.4 inches)	60%	very high
May Weather	14°C (58°F)	95 mm (3.8 inches)	74%	very high
June Weather	21°C (71°F)	34 mm (1.3 inches)	82%	extreme
July Weather	25°C (77°F)	30 mm (1.2 inches)	82%	extreme
August Weather	23°C (74°F)	32 mm (1.3 inches)	84%	very high
September Weather	20°C (68°F)	15 mm (0.6 inches)	75%	very high
October Weather	10°C (49°F)	24 mm (0.9 inches)	73%	high
November Weather	5°C (41°F)	15 mm (0.6 inches)	74%	moderate
December Weather	0°C (33°F)	10 mm (0.4 inches)	77%	moderate