September Weather in Granby, United States

Last updated: June 24, 2025

In September, the average temperature in Granby, United States is a mild 11°C (51°F). However, temperatures can fluctuate significantly, with a minimum of -6°C (22°F) and a maximum reaching 26°C (80°F). Visitors can expect 26 mm (1.0 in) of precipitation over approximately 4 days, accompanied by a comfortable average humidity of 65%.

September Temperature in Granby

In September in Granby, the average temperature is 11°C (51°F). Maximums can reach 26°C (80°F) and minimums can be as low as -6°C (22°F). Travelers should prepare for a wide range of temperatures and pack accordingly to ensure comfort during their visit.

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

The chart illustrates September temperature patterns in Granby, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Granby, September typically has an average temperature of 11°C (51°F), with highs reaching up to 26°C (80°F) and lows dropping to around -6°C (22°F).

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

September Precipitation in Granby

In Granby in September, the precipitation amount is 26 mm (1.0 in) over the course of 4 days.

September Precipitation Trends in Granby

The chart displays monthly precipitation patterns in Granby, 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 Granby, September typically receives around 26 mm (1.0 inches) of precipitation spread over approximately 4 days.

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

Choose your preferred precipitation unit

Millimeters (mm) Inches (in)

September Humidity in Granby

In Granby in September, humidity is 65%. With an average temperature of 11°C (51°F), this humidity feels like a refreshing yet brisk embrace, making it ideal for exploring the sights while layered in comfortable clothing.

September Average Humidity in Granby

This chart illustrates the average monthly humidity levels in Granby, 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 Granby is approximately 65%, 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 Granby

In Granby in September, the maximum UV index reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more detailed information, you can check the Hourly UV Index in Granby.

Maximum UV Index Levels in Granby for September

The chart shows the monthly maximum UV Index (UVI) for Granby 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 Granby typically reaches 10, which falls under the very high exposure category.

Data source: Granby 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 Granby Compares to Other Months

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

This table compares monthly weather conditions in Granby, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	-9°C (16°F)	38 mm (1.5 inches)	88%	moderate
February Weather	-8°C (19°F)	54 mm (2.1 inches)	87%	high
March Weather	-3°C (27°F)	58 mm (2.3 inches)	81%	very high
April Weather	0°C (32°F)	62 mm (2.4 inches)	76%	extreme
May Weather	4°C (39°F)	64 mm (2.5 inches)	66%	extreme
June Weather	11°C (52°F)	33 mm (1.3 inches)	58%	extreme
July Weather	15°C (59°F)	25 mm (1.0 inches)	52%	extreme
August Weather	14°C (58°F)	27 mm (1.1 inches)	56%	extreme
September Weather	11°C (51°F)	26 mm (1.0 inches)	65%	very high
October Weather	2°C (36°F)	50 mm (2.0 inches)	76%	high
November Weather	-4°C (24°F)	40 mm (1.6 inches)	82%	moderate
December Weather	-9°C (15°F)	41 mm (1.6 inches)	89%	moderate