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 decrease of average high-temperatures is mild in September, with a decline from a moderately hot 75.4°F (24.1°C) in August to an enjoyable 65.7°F (18.7°C). September nights bring a pronounced temperature shift, with averages hovering around a cold 41.5°F (5.3°C).Humidity
In Challis, the average relative humidity in September is 45%.Rainfall
In September, the rain falls for 6.9 days. Throughout September, 0.51" (13mm) of precipitation is accumulated. Throughout the year, there are 75.7 rainfall days, and 6.38" (162mm) of precipitation is accumulated.Snowfall
January through June, September through December are months with snowfall in Challis. September is the first month it typically snows. Throughout September, in the average 0.5 snowfall days, it receives 0.67" (17mm) of snow. Throughout the year, in Challis, there are 51.7 snowfall days, and 18.62" (473mm) of snow is accumulated.Daylight
The average length of the day in September is 12h and 30min.On the first day of September, sunrise is at 7:00 am and sunset at 8:12 pm. On the last day of the month, sunrise is at 7:34 am and sunset at 7:18 pm MDT.
Sunshine
In Challis, the average sunshine in September 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 vulnerability from exposure to the Sun's UV radiation for ordinary individuals.Note: The maximum daily UV index, 3 in September, converts into the following recommendations:
Prioritize safety - Suggestions to prevent sun damage are offered. The Sun's harshest UV rays are around midday; it's wise to seek shade and limit time outdoors. Tightly woven clothing, when worn loosely, shields effectively against the Sun. Be cautious! The UV radiation from the Sun can be magnified almost twofold by snow reflection.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are the temperatures in September?
What is the average humidity in September?
How many days does it rain in September?
When does it start to snow?
What is the average length of the day in September?
When is the sunrise / sunset in September in Challis?
How long on average sun shines in September?
What is the UV index reading in September?
Average temperature in September
Challis, ID
- Average high temperature in September: 65.7°F
The warmest month (with the highest average high temperature) is July (76.6°F).
The month with the lowest average high temperature is December (26.1°F).
- Average low temperature in September: 41.5°F
The month with the highest average low temperature is August (47.8°F).
The coldest month (with the lowest average low temperature) is January (8.1°F).
Average pressure in September
Challis, ID
- Average pressure in September: 29.98"Hg
The month with the highest atmospheric pressure is January (30.27"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).
Average wind speed in September
Challis, ID
- Average wind speed in September: 5.2mph
The windiest months (with the highest average wind speed) are June and July (5.7mph).
The calmest month (with the lowest average wind speed) is January (4.8mph).
Average humidity in September
Challis, ID
- Average humidity in September: 45%
The month with the highest relative humidity is February (87%).
The months with the lowest relative humidity are July and August (38%).
Average rainfall in September
Challis, ID
- Average rainfall in September: 0.51"
The wettest month (with the highest rainfall) is June (1.1").
The driest month (with the least rainfall) is July (0.28").
Average rainfall days in September
Challis, ID
- Average rainfall days in September: 6.9 days
The month with the highest number of rainy days is June (10.2 days).
The month with the least rainy days is January (3.8 days).
Average snowfall in September
Challis, ID
- Average snowfall in September: 0.67"
The month with the highest snowfall is February (3.54").
The months with the least snowfall are July and August (0").
Average snowfall days in September
Challis, ID
- Average snowfall days in September: 0.5 days
The month with the highest number of snowfall days is December (10.1 days).
The months with the least snowfall days are July and August (0 days).
Average daylight in September /
Average sunshine in September
Challis, ID
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 30min).
The month with the shortest days is December (Average daylight: 8h and 54min).
- Average sunshine in September: 9h and 3min
The month with the most sunshine is July (Average sunshine: 11h and 54min).
The month with the least sunshine is January (Average sunshine: 5h and 48min).
Average sunshine days in September
Challis, ID
- Average sunshine days in September: 21.6 days
The month with the most sunshine days is July (24.1 days).
The months with the least sunshine days are March and April (17.2 days).
Average UV index in September
Challis, ID
- 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, March, April, October, November and December (UV index 2).
Average cloud cover in September
Challis, ID
- Average cloud cover in September: 16
The month with the most cloud cover is February (Cloud cover 44).
The month with the least cloud cover is July (Cloud cover 11).
Average visibility in September
Challis, ID
- Average visibility in September: 6mi
The months with the highest visibility are April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January and February (4mi).
Challis, Idaho, USA
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