Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average snowfall in September
- Average snowfall days in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
The arrival of September signals a shift in temperature, down from 84.7°F (29.3°C) in August to a still moderately hot 74.7°F (23.7°C). In September, Custer reports a consistent average low-temperature of 54.9°F (12.7°C) during the nights.Humidity
In September, the average relative humidity in Custer is 42%.Rainfall
In Custer, in September, during 7.9 rainfall days, 1.26" (32mm) of precipitation is typically accumulated. Throughout the year, in Custer, there are 107 rainfall days, and 12.17" (309mm) of precipitation is accumulated.Snowfall
Months with snowfall in Custer are January through May, September through December. September is the first month it typically snows in Custer, Montana. Throughout September, in the average 0.2 snowfall days, it receives 0.08" (2mm) of snow. Throughout the year, there are 48.3 snowfall days, and 17.68" (449mm) of snow is accumulated.Daylight
The average length of the day in September is 12h and 31min.On the first day of the month, sunrise is at 6:31 am and sunset at 7:48 pm. On the last day of September, sunrise is at 7:08 am and sunset at 6:51 pm MDT.
Sunshine
The average sunshine in September in Custer, Montana, is 10.4h.UV index
The average daily maximum UV index in September in Custer is 4. A UV Index value of 3 to 5 symbolizes a medium vulnerability from unprotected exposure to Sun's UV rays for average individuals.Note: In September, the maximum UV index of 4 suggests these recommendations:
Take necessary precautions - Protection from skin and eye injury is mandatory. Direct exposure to the Sun during its peak hours around mid-day should be minimized for safety. Protect your eyes, ears, face, and neck from the Sun by wearing a wide-brimmed hat. Be vigilant! The reflective nature of snow can increase the Sun's UV radiation nearly twofold.
Frequently asked questions
What are September temperatures in Custer?
What is the average humidity in September in Custer?
How many days does it rain in September in Custer?
When does it start to snow in Custer?
What is the average length of the day in September in Custer?
When is the sunrise / sunset in September in Custer?
How many hours of sunshine does Custer have in September?
What is the UV index reading in September in Custer?
Average temperature in September
Custer, MT
- Average high temperature in September: 74.7°F
The warmest month (with the highest average high temperature) is July (86.5°F).
The months with the lowest average high temperature are January and December (31.1°F).
- Average low temperature in September: 54.9°F
The month with the highest average low temperature is July (64.2°F).
The coldest month (with the lowest average low temperature) is January (17.6°F).
Average pressure in September
Custer, MT
- Average pressure in September: 29.93"Hg
The month with the highest atmospheric pressure is January (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.84"Hg).
Average wind speed in September
Custer, MT
- Average wind speed in September: 8.8mph
The windiest month (with the highest average wind speed) is April (10.2mph).
The calmest months (with the lowest average wind speed) are July and August (8.2mph).
Average humidity in September
Custer, MT
- Average humidity in September: 42%
The month with the highest relative humidity is January (79%).
The month with the lowest relative humidity is August (38%).
Average rainfall in September
Custer, MT
- Average rainfall in September: 1.26"
The wettest month (with the highest rainfall) is May (1.85").
The driest month (with the least rainfall) is December (0.55").
Average rainfall days in September
Custer, MT
- Average rainfall days in September: 7.9 days
The month with the highest number of rainy days is May (14.3 days).
The month with the least rainy days is December (4.5 days).
Average snowfall in September
Custer, MT
- Average snowfall in September: 0.08"
The month with the highest snowfall is February (4.29").
The months with the least snowfall are June, July and August (0").
Average snowfall days in September
Custer, MT
- Average snowfall days in September: 0.2 days
The month with the highest number of snowfall days is February (10.6 days).
The months with the least snowfall days are June, July and August (0 days).
Average daylight in September /
Average sunshine in September
Custer, MT
- Average daylight in September: 12h and 3min
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 2min
The month with the most sunshine is July (Average sunshine: 11h and 48min).
The month with the least sunshine is February (Average sunshine: 5h and 12min).
Average sunshine days in September
Custer, MT
- Average sunshine days in September: 19 days
The month with the most sunshine days is November (19.2 days).
The month with the least sunshine days is April (13.5 days).
Average UV index in September
Custer, MT
- Average UV index in September: 4
The month with the highest UV index is July (UV index 7).
The months with the lowest UV index are January, February, March, November and December (UV index 2).
Average cloud cover in September
Custer, MT
- Average cloud cover in September: 21
The month with the most cloud cover is February (Cloud cover 46).
The months with the least cloud cover are July and August (Cloud cover 15).
Average visibility in September
Custer, 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).
Custer, Montana, USA
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