September weather forecastBig Arm, MT
September
Weather in September
The first month of the autumn, September, is also an enjoyable month in Big Arm, Montana, with an average temperature varying between 42.3°F (5.7°C) and 67.6°F (19.8°C).Temperature
September brings a decrease in the average high-temperature, shifting from a moderately hot 78.6°F (25.9°C) in August to a refreshing 67.6°F (19.8°C). Big Arm in September observes a substantial swing from the daily highs, with average nighttime temperatures of 42.3°F (5.7°C).Humidity
The average relative humidity in September is 59%.Rainfall
In September, in Big Arm, the rain falls for 10.7 days. Throughout September, 0.94" (24mm) of precipitation is accumulated. In Big Arm, during the entire year, the rain falls for 160.2 days and collects up to 18.11" (460mm) of precipitation.Snowfall
Months with snowfall are January through May, September through December. September is the first month it typically snows. Throughout September, in the average 0.2 snowfall days, it receives 0.31" (8mm) of snow. In Big Arm, during the entire year, snow falls for 99 days and aggregates up to 47.28" (1201mm) of snow.Daylight
The average length of the day in September is 12h and 33min.On the first day of the month, sunrise is at 6:56 am and sunset at 8:17 pm. On the last day of September, sunrise is at 7:36 am and sunset at 7:17 pm MDT.
Sunshine
In September, the average sunshine is 9.4h.UV index
The average daily maximum UV index in September is 3. A UV Index value of 3 to 5 symbolizes a moderate threat to health from unsafe exposure to UV radiation for the average person.Note: In September, the maximum UV index of 3 translates into these guidelines:
Make use of precautions - Shielding skin and eyes from injury is a requirement. Avoiding direct sunlight during midday hours helps reduce the risk from intense UV radiation. Protect your eyes, ears, face, and neck from the Sun by wearing a wide-brimmed hat. Take careful note! The UV radiation of the Sun can be nearly doubled by snow reflection.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Big Arm, MT
- Average high temperature in September: 67.6°F
The warmest month (with the highest average high temperature) is July (79.3°F).
The month with the lowest average high temperature is December (27.9°F).
- Average low temperature in September: 42.3°F
The months with the highest average low temperature are July and August (48.9°F).
The coldest month (with the lowest average low temperature) is December (16.7°F).
Average pressure in September
Big Arm, MT
- Average pressure in September: 29.98"Hg
The month with the highest atmospheric pressure is January (30.17"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in September
Big Arm, MT
- Average wind speed in September: 3.9mph
The windiest month (with the highest average wind speed) is April (4.8mph).
The calmest month (with the lowest average wind speed) is August (3.7mph).
Average humidity in September
Big Arm, MT
- Average humidity in September: 59%
The month with the highest relative humidity is January (91%).
The month with the lowest relative humidity is August (51%).
Average rainfall in September
Big Arm, MT
- Average rainfall in September: 0.94"
The wettest month (with the highest rainfall) is June (2.2").
The driest months (with the least rainfall) are July and August (0.55").
Average rainfall days in September
Big Arm, MT
- Average rainfall days in September: 10.7 days
The months with the highest number of rainy days are March and April (18.8 days).
The month with the least rainy days is August (7 days).
Average snowfall in September
Big Arm, MT
- Average snowfall in September: 0.31"
The month with the highest snowfall is February (10.28").
The months with the least snowfall are June, July and August (0").
Average snowfall days in September
Big Arm, MT
- Average snowfall days in September: 0.2 days
The month with the highest number of snowfall days is December (19.8 days).
The months with the least snowfall days are June, July and August (0 days).
Average daylight in September /
Average sunshine in September
Big Arm, MT
- Average daylight in September: 12h and 36min
The month with the longest days is June (Average daylight: 15h and 54min).
The month with the shortest days is December (Average daylight: 8h and 30min).
- Average sunshine in September: 9h and 24min
The month with the most sunshine is July (Average sunshine: 11h and 54min).
The month with the least sunshine is January (Average sunshine: 4h and 30min).
Average sunshine days in September
Big Arm, MT
- Average sunshine days in September: 17.5 days
The month with the most sunshine days is July (21.3 days).
The month with the least sunshine days is March (6.4 days).
Average UV index in September
Big Arm, MT
- Average UV index in September: 3
The months with the highest UV index are June and July (UV index 5).
The months with the lowest UV index are January, February, November and December (UV index 1).
Average cloud cover in September
Big Arm, MT
- Average cloud cover in September: 22
The month with the most cloud cover is January (Cloud cover 54).
The months with the least cloud cover are July and August (Cloud cover 14).
Average visibility in September
Big Arm, MT
- Average visibility in September: 6mi
The months with the highest visibility are April, May, June, July, August, September and October (6mi).
The months with the lowest visibility are January, February and December (4mi).
