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September Weather in Granby, United States

Last updated: June 24, 2025

In Granby, United States, the average temperature in September hovers around 23°C (74°F). While the thermometer can dip to a cool minimum of 7°C (44°F), it may also peak at a sizzling 34°C (94°F). Expect about 63 mm (2.5 in) of precipitation spread over 6 days, contributing to an average humidity level of 64%.

September Temperature in Granby

In September in Granby, the average temperature is 23°C (74°F). Maximum temperatures can reach 34°C (94°F), while minimums can drop as low as 7°C (44°F). This diverse range of temperatures makes it an ideal time for travelers to enjoy both warm days and cool evenings.

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 23°C (74°F), with highs reaching up to 34°C (94°F) and lows dropping to around 7°C (44°F).
JanFebMarAprMayJunJulAugSepOctNovDec363850566776807773594742
Data source: Temperature data for Granby 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 Granby

In Granby in September, the precipitation amount is 63 mm (2.5 in) spread over a duration of 6 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 63 mm (2.5 inches) of precipitation spread over approximately 6 days.
JanFebMarAprMayJunJulAugSepOctNovDec84751451401748589111631466049
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Granby

In Granby in September, humidity is 64%. With an average temperature of 23°C (74°F), this humidity feels like a warm blanket wrapping around you, making outdoor exploration enjoyable yet slightly sticky, so it's best to stay hydrated and take breaks in the shade while traveling.

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 64%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec81%78%76%78%83%83%78%68%64%70%83%87%
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 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 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 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec36710101111109753
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.
 TemperaturePrecipitationHumidityUV
January Weather2°C (36°F)84 mm (3.3 inches)81%moderate
February Weather4°C (39°F)75 mm (2.9 inches)78%high
March Weather10°C (50°F)145 mm (5.7 inches)76%high
April Weather13°C (56°F)139 mm (5.5 inches)78%very high
May Weather19°C (67°F)174 mm (6.9 inches)83%very high
June Weather25°C (77°F)85 mm (3.3 inches)83%extreme
July Weather26°C (80°F)89 mm (3.5 inches)78%extreme
August Weather25°C (77°F)111 mm (4.4 inches)68%very high
September Weather23°C (74°F)63 mm (2.5 inches)64%very high
October Weather15°C (59°F)146 mm (5.8 inches)70%high
November Weather8°C (47°F)60 mm (2.3 inches)83%moderate
December Weather6°C (42°F)49 mm (1.9 inches)87%moderate

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