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 transition into September involves a small decrease in the average high-temperature, dipping slightly from a moderately hot 81.3°F (27.4°C) in August to an agreeable 72.7°F (22.6°C). Casper's temperature exhibits a stark contrast from daytime to nighttime, averaging lows of 50.9°F (10.5°C) in September.Humidity
In September, the average relative humidity in Casper is 40%.Rainfall
The months with the least rainfall in Casper, Wyoming, are January, August and September Rain falls for 7.6 days and accumulates 0.43" (11mm) of rain.Snowfall
January through May, September through December are months with snowfall in Casper, Wyoming. September is the first month it typically snows in Casper. Throughout September, in the average 0.2 snowfall days, it receives 0.12" (3mm) of snow. In Casper, during the entire year, snow falls for 61.5 days and aggregates up to 32.13" (816mm) of snow.Daylight
In September, the average length of the day is 12h and 29min.On the first day of the month, sunrise is at 6:30 am and sunset at 7:39 pm. On the last day of September, sunrise is at 7:02 am and sunset at 6:47 pm MDT.
Sunshine
In Casper, the average sunshine in September is 11.1h.UV index
In Casper, the average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a moderate health risk from unsafe exposure to UV radiation for average individuals.Note: In September, an average UV index of 4 transforms into the following instructions:
Make use of precautions - Suggestions to resist sunburn are communicated. The Sun is at its harshest during midday; protect yourself by staying in shaded areas and minimizing exposure. Sunglasses that guard against UVA and UVB rays are pivotal in minimizing sun-induced ocular damage. Be alert to the fact! The reflection from snow can nearly double the UV radiation of the Sun.
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Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the average September temperature in Casper?
What is the average humidity in September in Casper?
What is the driest month in Casper?
How many days does it rain in September in Casper?
When does it start snowing in Casper?
How many hours of daylight does Casper have in September?
When are sunrise and sunset in September in Casper?
How long on average sun shines in September in Casper?
What is the UV index intensity in September in Casper?
Average temperature in September
Casper, WY
- Average high temperature in September: 72.7°F
The warmest month (with the highest average high temperature) is July (83.5°F).
The month with the lowest average high temperature is December (28.4°F).
- Average low temperature in September: 50.9°F
The month with the highest average low temperature is July (59.5°F).
The coldest month (with the lowest average low temperature) is December (15.1°F).
Average pressure in September
Casper, WY
- Average pressure in September: 29.94"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.85"Hg).
Average wind speed in September
Casper, WY
- Average wind speed in September: 9.4mph
The windiest month (with the highest average wind speed) is January (12.1mph).
The calmest months (with the lowest average wind speed) are July and August (8.5mph).
Average humidity in September
Casper, WY
- Average humidity in September: 40%
The month with the highest relative humidity is January (79%).
The month with the lowest relative humidity is August (37%).
Average rainfall in September
Casper, WY
- Average rainfall in September: 0.43"
The wettest month (with the highest rainfall) is May (1.77").
The driest months (with the least rainfall) are January, August and September (0.43").
Average rainfall days in September
Casper, WY
- Average rainfall days in September: 7.6 days
The month with the highest number of rainy days is May (14.1 days).
The month with the least rainy days is January (3.6 days).
Average snowfall in September
Casper, WY
- Average snowfall in September: 0.12"
The month with the highest snowfall is November (5.47").
The months with the least snowfall are June, July and August (0").
Average snowfall days in September
Casper, WY
- Average snowfall days in September: 0.2 days
The month with the highest number of snowfall days is February (11.2 days).
The months with the least snowfall days are June, July and August (0 days).
Average daylight in September /
Average sunshine in September
Casper, WY
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 18min).
The month with the shortest days is December (Average daylight: 9h and 6min).
- Average sunshine in September: 11h and 1min
The months with the most sunshine are July and August (Average sunshine: 11h and 54min).
The month with the least sunshine is February (Average sunshine: 6h and 6min).
Average sunshine days in September
Casper, WY
- Average sunshine days in September: 19.2 days
The month with the most sunshine days is December (20.5 days).
The month with the least sunshine days is May (11.9 days).
Average UV index in September
Casper, WY
- Average UV index in September: 4
The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, March, April, October, November and December (UV index 2).
Average cloud cover in September
Casper, WY
- Average cloud cover in September: 14
The month with the most cloud cover is February (Cloud cover 36).
The month with the least cloud cover is August (Cloud cover 13).
Average visibility in September
Casper, WY
- 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).
Casper, Wyoming, USA
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