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
Transition from August to September is accompanied by a temperature drop, with average high-temperatures decreasing from a pleasant 73.2°F (22.9°C) to a comfortable 63.7°F (17.6°C). Throughout the nights in September, an average low-temperature of 43.2°F (6.2°C) is noted.Humidity
In September, the average relative humidity is 44%.Rainfall
In Ketchum, in September, it is raining for 8.8 days, with typically 0.87" (22mm) of accumulated precipitation. Throughout the year, there are 107.7 rainfall days, and 15.63" (397mm) of precipitation is accumulated.Snowfall
Months with snowfall are January through June, September through December. September is the first month it typically snows. Throughout September, in the average 0.5 snowfall days, it receives 0.55" (14mm) of snow. Throughout the year, there are 88.2 snowfall days, and 69.45" (1764mm) of snow is accumulated.Daylight
In September, the average length of the day is 12h and 29min.On the first day of September, sunrise is at 7:02 am and sunset at 8:12 pm. On the last day of the month, sunrise is at 7:34 am and sunset at 7:19 pm MDT.
Sunshine
In Ketchum, the average sunshine in September is 9.4h.UV index
In September, the average daily maximum UV index is 3. A UV Index of 3 to 5 symbolizes a medium vulnerability from exposure to the Sun's UV radiation for the ordinary person.Note: The maximum daily UV index, 3 in September, converts into the following recommendations:
Be vigilant - A duty to shield skin and eyes from injury exists. To prevent harmful UV exposure, minimize direct contact with the Sun around midday. In the presence of strong sunlight, it's crucial to wear sunglasses that ward off UVA and UVB rays. Take heed! Reflection from the snow can almost amplify the Sun's UV radiation by double.
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 much does it rain in September?
When does it start snowing?
What is the average length of the day in September?
When are sunrise and sunset in September?
How long on average sun shines in September in Ketchum?
How high is the UV index in September?
Average temperature in September
Ketchum, ID
- Average high temperature in September: 63.7°F
The warmest month (with the highest average high temperature) is July (74.1°F).
The month with the lowest average high temperature is December (25°F).
- Average low temperature in September: 43.2°F
The months with the highest average low temperature are July and August (50.5°F).
The coldest month (with the lowest average low temperature) is January (8.4°F).
Average pressure in September
Ketchum, ID
- Average pressure in September: 29.95"Hg
The month with the highest atmospheric pressure is January (30.27"Hg).
The month with the lowest atmospheric pressure is June (29.89"Hg).
Average wind speed in September
Ketchum, ID
- Average wind speed in September: 5.4mph
The windiest month (with the highest average wind speed) is July (6.3mph).
The calmest month (with the lowest average wind speed) is January (4.5mph).
Average humidity in September
Ketchum, ID
- Average humidity in September: 44%
The month with the highest relative humidity is February (87%).
The month with the lowest relative humidity is August (37%).
Average rainfall in September
Ketchum, ID
- Average rainfall in September: 0.87"
The wettest month (with the highest rainfall) is March (2.01").
The driest month (with the least rainfall) is July (0.43").
Average rainfall days in September
Ketchum, ID
- Average rainfall days in September: 8.8 days
The month with the highest number of rainy days is May (14.8 days).
The month with the least rainy days is July (5.9 days).
Average snowfall in September
Ketchum, ID
- Average snowfall in September: 0.55"
The month with the highest snowfall is February (15").
The months with the least snowfall are July and August (0").
Average snowfall days in September
Ketchum, ID
- Average snowfall days in September: 0.5 days
The month with the highest number of snowfall days is March (16 days).
The months with the least snowfall days are July and August (0 days).
Average daylight in September /
Average sunshine in September
Ketchum, ID
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 24min).
The month with the shortest days is December (Average daylight: 9h and 0min).
- Average sunshine in September: 9h and 2min
The month with the most sunshine is July (Average sunshine: 12h and 0min).
The month with the least sunshine is January (Average sunshine: 5h and 42min).
Average sunshine days in September
Ketchum, ID
- Average sunshine days in September: 19.7 days
The month with the most sunshine days is July (20.8 days).
The month with the least sunshine days is April (11.1 days).
Average UV index in September
Ketchum, ID
- Average UV index in September: 3
The months with the highest UV index are June and July (UV index 5).
The month with the lowest UV index is February (UV index 1).
Average cloud cover in September
Ketchum, ID
- Average cloud cover in September: 15
The month with the most cloud cover is February (Cloud cover 44).
The month with the least cloud cover is July (Cloud cover 10).
Average visibility in September
Ketchum, 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, February and December (4mi).
Ketchum, Idaho, USA
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