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 onset of September brings a small change in high-temperatures, falling from a moderately hot 78.3°F (25.7°C) in August to a comfortable 67.6°F (19.8°C). In September, the nighttime temperature plummets remarkably from the daily apex to a steady average of 41.2°F (5.1°C).Humidity
In September, the average relative humidity is 52%.Rainfall
In Mammoth, in September, it is raining for 10.3 days, with typically 0.98" (25mm) of accumulated precipitation. Throughout the year, there are 158 rainfall days, and 12.2" (310mm) of precipitation is accumulated.Snowfall
In Mammoth, snow does not fall in May through September.Daylight
In Mammoth, the average length of the day in September is 12h and 31min.On the first day of the month, sunrise is at 6:50 am and sunset at 8:05 pm. On the last day of September, sunrise is at 7:26 am and sunset at 7:09 pm MDT.
Sunshine
The average sunshine in September is 9.8h.UV index
In September, the average daily maximum UV index in Mammoth is 3. A UV Index estimate of 3 to 5 represents a medium vulnerability from unprotected exposure to Sun's UV rays for the ordinary person.Note: A daily maximum UV index of 3 in September translates into the following instructions:
Prioritize safety - The need to safeguard skin and eyes from harm is emphasized. Given the potency of the midday Sun's UV radiation, one should avoid prolonged exposure. In bright sunlight, prioritize sunglasses that grant protection from UVA and UVB radiation.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the average September temperature?
What is the average humidity in September?
How much does it rain in September?
When it does not snow?
Does it snow in September?
How many hours of daylight does Mammoth have in September?
When is the sunrise / sunset in September?
How many hours of sunshine does Mammoth have in September?
How high is the UV index in September in Mammoth?
Average temperature in September
Mammoth, MT
- Average high temperature in September: 67.6°F
The warmest month (with the highest average high temperature) is July (79.5°F).
The month with the lowest average high temperature is December (26.4°F).
- Average low temperature in September: 41.2°F
The month with the highest average low temperature is July (47.7°F).
The coldest month (with the lowest average low temperature) is December (11.3°F).
Average pressure in September
Mammoth, MT
- Average pressure in September: 29.99"Hg
The month with the highest atmospheric pressure is January (30.23"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in September
Mammoth, MT
- Average wind speed in September: 5mph
The windiest month (with the highest average wind speed) is November (6.3mph).
The calmest month (with the lowest average wind speed) is August (4.6mph).
Average humidity in September
Mammoth, MT
- Average humidity in September: 52%
The month with the highest relative humidity is January (85%).
The months with the lowest relative humidity are July and August (46%).
Average rainfall in September
Mammoth, MT
- Average rainfall in September: 0.98"
The wettest month (with the highest rainfall) is May (1.85").
The driest month (with the least rainfall) is January (0.59").
Average rainfall days in September
Mammoth, MT
- Average rainfall days in September: 10.3 days
The month with the highest number of rainy days is April (18.6 days).
The month with the least rainy days is August (8.6 days).
Average snowfall in September
Mammoth, MT
- Average snowfall in September: 0"
The month with the highest snowfall is February (1.81").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Mammoth, MT
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (6.2 days).
The months with the least snowfall days are May, June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Mammoth, MT
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 36min).
The month with the shortest days is December (Average daylight: 8h and 48min).
- Average sunshine in September: 9h and 5min
The month with the most sunshine is July (Average sunshine: 11h and 54min).
The month with the least sunshine is December (Average sunshine: 6h and 0min).
Average sunshine days in September
Mammoth, MT
- Average sunshine days in September: 16.4 days
The month with the most sunshine days is July (17.8 days).
The month with the least sunshine days is April (7.8 days).
Average UV index in September
Mammoth, MT
- Average UV index in September: 3
The month with the highest UV index is 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
Mammoth, MT
- Average cloud cover in September: 19
The month with the most cloud cover is February (Cloud cover 42).
The months with the least cloud cover are July and August (Cloud cover 14).
Average visibility in September
Mammoth, MT
- Average visibility in September: 6mi
The months with the highest visibility are March, April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January, February and December (5mi).
Mammoth, Montana, USA
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