September weather forecastHeron, MT
September
Weather in September
September, the first month of the autumn in Heron, is still a refreshing month, with an average temperature varying between 41.7°F (5.4°C) and 67.8°F (19.9°C).Temperature
Heron observes a minor decrease in the average high-temperature with the arrival of September, falling from August's warm 78.3°F (25.7°C) to a comfortable 67.8°F (19.9°C). Throughout September nights, Heron reports a steady thermal contrast from the day, with an average low-temperature of 41.7°F (5.4°C).Humidity
In September, the average relative humidity is 63%.Rainfall
In Heron, during September, the rain falls for 10.7 days and regularly aggregates up to 1.14" (29mm) of precipitation. In Heron, during the entire year, the rain falls for 161.9 days and collects up to 27.48" (698mm) of precipitation.Snowfall
January through May, September through December are months with snowfall. September is the first month it typically snows. Throughout September, in the average 0.3 snowfall days, it receives 0.28" (7mm) of snow. In Heron, during the entire year, snow falls for 80.8 days and aggregates up to 60" (1524mm) of snow.Daylight
In September, the average length of the day is 12h and 33min.On the first day of September, sunrise is at 7:03 am and sunset at 8:24 pm. On the last day of the month, sunrise is at 7:42 am and sunset at 7:24 pm MDT.
Sunshine
In September, the average sunshine is 9.5h.UV index
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 rays for average individuals.Note: The UV index of 3 during September translates into the following guidance:
Heed the precautions - Suggestions to avoid sunburn are made. To guard against the harmful effects of the Sun, minimize exposure during midday. Sun-related eye harm can be minimized with proper sunglasses offering UVA and UVB coverage. Be aware! The reflective nature of snow can magnify the Sun's UV radiation almost twofold.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Heron, MT
- Average high temperature in September: 67.8°F
The warmest month (with the highest average high temperature) is August (78.3°F).
The month with the lowest average high temperature is December (29.3°F).
- Average low temperature in September: 41.7°F
The month with the highest average low temperature is August (49.1°F).
The coldest month (with the lowest average low temperature) is December (18.7°F).
Average pressure in September
Heron, MT
- Average pressure in September: 29.97"Hg
The month with the highest atmospheric pressure is January (30.19"Hg).
The months with the lowest atmospheric pressure are June and August (29.92"Hg).
Average wind speed in September
Heron, MT
- Average wind speed in September: 3.9mph
The windiest month (with the highest average wind speed) is April (4.5mph).
The calmest month (with the lowest average wind speed) is December (3.5mph).
Average humidity in September
Heron, MT
- Average humidity in September: 63%
The month with the highest relative humidity is January (94%).
The month with the lowest relative humidity is August (52%).
Average rainfall in September
Heron, MT
- Average rainfall in September: 1.14"
The wettest month (with the highest rainfall) is December (3.66").
The driest month (with the least rainfall) is August (0.55").
Average rainfall days in September
Heron, MT
- Average rainfall days in September: 10.7 days
The month with the highest number of rainy days is April (19.3 days).
The month with the least rainy days is August (6.9 days).
Average snowfall in September
Heron, MT
- Average snowfall in September: 0.28"
The month with the highest snowfall is January (15.87").
The months with the least snowfall are June, July and August (0").
Average snowfall days in September
Heron, MT
- Average snowfall days in September: 0.3 days
The month with the highest number of snowfall days is December (19.5 days).
The months with the least snowfall days are June, July and August (0 days).
Average daylight in September /
Average sunshine in September
Heron, MT
- Average daylight in September: 12h and 36min
The month with the longest days is June (Average daylight: 16h and 0min).
The month with the shortest days is December (Average daylight: 8h and 24min).
- Average sunshine in September: 9h and 30min
The month with the most sunshine is August (Average sunshine: 11h and 48min).
The month with the least sunshine is January (Average sunshine: 3h and 12min).
Average sunshine days in September
Heron, MT
- Average sunshine days in September: 17.5 days
The month with the most sunshine days is July (20.9 days).
The month with the least sunshine days is March (7.1 days).
Average UV index in September
Heron, 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, November and December (UV index 1).
Average cloud cover in September
Heron, MT
- Average cloud cover in September: 25
The month with the most cloud cover is January (Cloud cover 67).
The month with the least cloud cover is August (Cloud cover 14).
Average visibility in September
Heron, MT
- Average visibility in September: 6mi
The months with the highest visibility are May, June, July, August and September (6mi).
The months with the lowest visibility are January, February and December (3mi).
