September weather forecastGranby, CO
September
Weather in September
September in Granby, Colorado, marks the advent of the fall season, thereby infusing a more calming and serene aura into the cityscape. The temperature sees a considerable retreat from the summer heat, reducing the maximum average temperature to 64.4°F (18°C). Concurrently, the precipitation and the snowfall slightly rise, signifying an early arrival of the anticipated frosty months. Increased daylight hours keep the city illuminated throughout the day, while the slowly building cloud cover foretells of the coming winter. Thus, September serves as an alluring crossover from the summer heat to the winter chills, offering the best of both the seasons.Temperature
September brings a minor shift in the average high-temperature in Granby, adjusting from an agreeable 71.2°F (21.8°C) in August to a refreshing 64.4°F (18°C). Granby notes a substantial temperature decline from the daytime peaks throughout September, with an average nighttime temperature of 36.9°F (2.7°C).Humidity
The average relative humidity in September is 52%.Rainfall
In Granby, during September, the rain falls for 7.1 days and regularly aggregates up to 0.59" (15mm) of precipitation. Throughout the year, there are 96.3 rainfall days, and 11.54" (293mm) of precipitation is accumulated.Snowfall
January through June, August through December are months with snowfall. In Granby, in September, snow falls for 2 days, with typically accumulated 0.87" (22mm) of snow. Throughout the year, in Granby, there are 110.7 snowfall days, and 59.88" (1521mm) of snow is accumulated.Daylight
In September, the average length of the day is 12h and 26min.On the first day of the month, sunrise is at 6:32 am and sunset at 7:34 pm. On the last day of September, in Granby, sunrise is at 6:59 am and sunset at 6:47 pm MDT.
Sunshine
The average sunshine in September is 11.2h.UV index
In Granby, the average daily maximum UV index in September is 3. A UV Index of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV radiation for ordinary individuals.Note: The maximum UV index, 3 during September, leads to the following recommendations:
Make use of precautions - It is urged to ward off sun damage. Being in direct Sun during midday can be harmful due to intense solar radiation; take precautions. Sunglasses providing both UVA and UVB protection are non-negotiable on sunlit days. Warning! The reflection from snow can nearly magnify the Sun's UV radiation twofold.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Granby, CO
- Average high temperature in September: 64.4°F
The warmest month (with the highest average high temperature) is July (72.3°F).
The month with the lowest average high temperature is December (24.6°F).
- Average low temperature in September: 36.9°F
The month with the highest average low temperature is July (43.7°F).
The coldest month (with the lowest average low temperature) is January (4.3°F).
Average pressure in September
Granby, CO
- Average pressure in September: 30.03"Hg
The month with the highest atmospheric pressure is January (30.19"Hg).
The months with the lowest atmospheric pressure are April, May and June (29.93"Hg).
Average wind speed in September
Granby, CO
- Average wind speed in September: 5.5mph
The windiest month (with the highest average wind speed) is February (7mph).
The calmest month (with the lowest average wind speed) is August (5mph).
Average humidity in September
Granby, CO
- Average humidity in September: 52%
The month with the highest relative humidity is February (87%).
The month with the lowest relative humidity is June (49%).
Average rainfall in September
Granby, CO
- Average rainfall in September: 0.59"
The wettest month (with the highest rainfall) is May (1.73").
The driest month (with the least rainfall) is August (0.55").
Average rainfall days in September
Granby, CO
- Average rainfall days in September: 7.1 days
The month with the highest number of rainy days is May (12.8 days).
The month with the least rainy days is October (4.9 days).
Average snowfall in September
Granby, CO
- Average snowfall in September: 0.87"
The month with the highest snowfall is April (10.94").
The month with the least snowfall is July (0").
Average snowfall days in September
Granby, CO
- Average snowfall days in September: 2 days
The month with the highest number of snowfall days is February (16.1 days).
The month with the least snowfall days is July (0 days).
Average daylight in September /
Average sunshine in September
Granby, CO
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 15h and 0min).
The month with the shortest days is December (Average daylight: 9h and 24min).
- Average sunshine in September: 11h and 12min
The months with the most sunshine are July and August (Average sunshine: 11h and 48min).
The month with the least sunshine is February (Average sunshine: 6h and 12min).
Average sunshine days in September
Granby, CO
- Average sunshine days in September: 19.5 days
The months with the most sunshine days are September and November (19.5 days).
The month with the least sunshine days is May (9.5 days).
Average UV index in September
Granby, CO
- Average UV index in September: 3
The months with the highest UV index are June, July and August (UV index 4).
The months with the lowest UV index are January, February, March, April, October, November and December (UV index 2).
Average cloud cover in September
Granby, CO
- Average cloud cover in September: 15
The month with the most cloud cover is February (Cloud cover 41).
The month with the least cloud cover is September (Cloud cover 15).
Average visibility in September
Granby, CO
- Average visibility in September: 6mi
The months with the highest visibility are May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January, February, March, April and December (5mi).
