September weather forecastGreycliff, MT
September
Weather in September
September, the first month of the autumn in Greycliff, is still a comfortable month, with an average temperature varying between 45.3°F (7.4°C) and 66.7°F (19.3°C).Temperature
The transition into September involves a decrease in the average high-temperature, falling from a warm 76.6°F (24.8°C) in August to an enjoyable 66.7°F (19.3°C). In Greycliff, September's nights observe an average temperature dip to a frosty 45.3°F (7.4°C).Humidity
In September, the average relative humidity is 51%.Rainfall
In September, in Greycliff, the rain falls for 9.8 days. Throughout September, 1.1" (28mm) of precipitation is accumulated. In Greycliff, during the entire year, the rain falls for 129.6 days and collects up to 15.83" (402mm) of precipitation.Snowfall
Months with snowfall are January through May, September through December. September is the first month it typically snows in Greycliff. Throughout September, in the average 1 snowfall days, it receives 0.51" (13mm) of snow. Throughout the year, in Greycliff, there are 67.6 snowfall days, and 38.19" (970mm) of snow is accumulated.Daylight
In September, the average length of the day in Greycliff is 12h and 31min.On the first day of the month, sunrise is at 6:41 am and sunset at 7:56 pm. On the last day of September, sunrise is at 7:17 am and sunset at 7:00 pm MDT.
Sunshine
In September, the average sunshine is 10.2h.UV index
The average daily maximum UV index in September in Greycliff is 3. A UV Index of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV radiation for the average person.Note: The daily high UV index of 3 during September translates into the following recommendations:
Take measures. Individuals with light skin might experience burns in under 30 minutes. For skin protection, it's recommended to minimize Sun exposure during its peak hours around midday. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. Remember this! The UV radiation of the Sun can be nearly doubled by the reflective properties of snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Greycliff, MT
- Average high temperature in September: 66.7°F
The warmest month (with the highest average high temperature) is July (78.6°F).
The month with the lowest average high temperature is December (28.4°F).
- Average low temperature in September: 45.3°F
The month with the highest average low temperature is August (52.9°F).
The coldest month (with the lowest average low temperature) is February (15.3°F).
Average pressure in September
Greycliff, MT
- Average pressure in September: 29.96"Hg
The months with the highest atmospheric pressure are January and December (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.88"Hg).
Average wind speed in September
Greycliff, MT
- Average wind speed in September: 6.9mph
The windiest month (with the highest average wind speed) is January (11.1mph).
The calmest month (with the lowest average wind speed) is July (5.9mph).
Average humidity in September
Greycliff, MT
- Average humidity in September: 51%
The month with the highest relative humidity is February (80%).
The month with the lowest relative humidity is August (47%).
Average rainfall in September
Greycliff, MT
- Average rainfall in September: 1.1"
The wettest month (with the highest rainfall) is May (3.15").
The driest month (with the least rainfall) is January (0.47").
Average rainfall days in September
Greycliff, MT
- Average rainfall days in September: 9.8 days
The month with the highest number of rainy days is May (19.8 days).
The months with the least rainy days are January and December (5.3 days).
Average snowfall in September
Greycliff, MT
- Average snowfall in September: 0.51"
The month with the highest snowfall is March (7.09").
The months with the least snowfall are June, July and August (0").
Average snowfall days in September
Greycliff, MT
- Average snowfall days in September: 1 days
The month with the highest number of snowfall days is February (12.9 days).
The months with the least snowfall days are June, July and August (0 days).
Average daylight in September /
Average sunshine in September
Greycliff, MT
- Average daylight in September: 12h and 30min
The month with the longest days is June (Average daylight: 15h and 42min).
The month with the shortest days is December (Average daylight: 8h and 42min).
- Average sunshine in September: 10h and 12min
The month with the most sunshine is July (Average sunshine: 11h and 48min).
The months with the least sunshine are January, February and December (Average sunshine: 6h and 12min).
Average sunshine days in September
Greycliff, MT
- Average sunshine days in September: 17.8 days
The month with the most sunshine days is January (19.8 days).
The month with the least sunshine days is May (7.7 days).
Average UV index in September
Greycliff, MT
- Average UV index in September: 3
The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January, February, March, April, October, November and December (UV index 2).
Average cloud cover in September
Greycliff, MT
- Average cloud cover in September: 21
The month with the most cloud cover is February (Cloud cover 41).
The months with the least cloud cover are July and August (Cloud cover 16).
Average visibility in September
Greycliff, MT
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
