September weather forecast
Jackson, MT

Share

Weather in September

The first month of the autumn, September, is still a refreshing month in Jackson, Montana, with an average temperature fluctuating between 65.3°F (18.5°C) and 40.6°F (4.8°C).

Temperature

A decrease in the average high-temperature is observed during September, shifting from a moderately hot 74.7°F (23.7°C) in August to a refreshing 65.3°F (18.5°C). Despite substantial daily fluctuations, the average low-temperature is a wintry 40.6°F (4.8°C) during September.

Humidity

In Jackson, the average relative humidity in September is 50%.

Rainfall

In Jackson, in September, it is raining for 9.4 days, with typically 0.94" (24mm) of accumulated precipitation. In Jackson, during the entire year, the rain falls for 129.5 days and collects up to 12.4" (315mm) of precipitation.

Snowfall

January through May, September through December are months with snowfall. September is the first month it typically snows. Throughout September, in the average 0.3 snowfall days, it receives 0.43" (11mm) of snow. Throughout the year, there are 63.5 snowfall days, and 22.76" (578mm) 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 6:56 am and sunset at 8:10 pm. On the last day of September, sunrise is at 7:31 am and sunset at 7:15 pm MDT.

Sunshine

In Jackson, the average sunshine in September is 9.4h.

UV index

In September, the average daily maximum UV index is 3. A UV Index reading of 3 to 5 represents a medium health hazard from exposure to the Sun's UV radiation for average individuals.
Note: The UV index of 3 during September translates into the following guidance:
Exercise prevention - Precautions against solar damage are endorsed. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. Tightly woven clothing, when worn loosely, shields effectively against the Sun. Be informed! The Sun's UV radiation can be nearly doubled due to the reflection from snow.
Updated: Aug 28, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the average September temperature?

The average high-temperature, in September, in Jackson, is 65.3°F (18.5°C), while the average low-temperature is 40.6°F (4.8°C).

What is the average humidity in September?

The average relative humidity in September is 50%.

How much does it rain in September?

In Jackson, in September, during 9.4 rainfall days, 0.94" (24mm) of precipitation is typically accumulated.

When does it start to snow?

September is the first month it typically snows. Throughout September, in the average 0.3 snowfall days, it receives 0.43" (11mm) of snow.

What is the average length of the day in September?

The average day length in September is 12h and 31min.

When is the sunrise / sunset in September?

In September, on the first day of the month, sunrise is at 6:56 am and sunset at 8:10 pm. On the last day of the month, sunrise is at 7:31 am and sunset at 7:15 pm MDT.

How many hours of sunshine does Jackson have in September?

In Jackson, the average sunshine duration in September is 9.4h.

What is the UV index reading in September?

In September, the average daily maximum UV index in Jackson is 3. A UV Index estimate of 3 to 5 represents a moderate vulnerability from unprotected exposure to UV radiation.
Average humidity
Average rainfall days
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Jackson, MT

Average temperature in September - Jackson, MT
  • Average high temperature in September: 65.3°F

The warmest month (with the highest average high temperature) is July (75.7°F).
The month with the lowest average high temperature is December (25.2°F).

  • Average low temperature in September: 40.6°F

The month with the highest average low temperature is August (47.5°F).
The coldest months (with the lowest average low temperature) are January and December (9.5°F).

Average pressure in September
Jackson, MT

Average pressure in September - Jackson, MT
  • Average pressure in September: 29.99"Hg

The month with the highest atmospheric pressure is January (30.25"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).

Average wind speed in September
Jackson, MT

Average wind speed in September - Jackson, MT
  • Average wind speed in September: 4.5mph

The windiest months (with the highest average wind speed) are March and April (5.2mph).
The calmest month (with the lowest average wind speed) is August (4.3mph).

Average humidity in September
Jackson, MT

Average humidity in September - Jackson, MT
  • Average humidity in September: 50%

The month with the highest relative humidity is February (89%).
The month with the lowest relative humidity is August (43%).

Average rainfall in September
Jackson, MT

Average rainfall in September - Jackson, MT
  • Average rainfall in September: 0.94"

The wettest month (with the highest rainfall) is June (2.05").
The driest months (with the least rainfall) are July and August (0.51").

Average rainfall days in September
Jackson, MT

Average rainfall days in September - Jackson, MT
  • Average rainfall days in September: 9.4 days

The month with the highest number of rainy days is May (18.3 days).
The month with the least rainy days is January (6.3 days).

Average snowfall in September
Jackson, MT

Average snowfall in September - Jackson, MT
  • Average snowfall in September: 0.43"

The month with the highest snowfall is February (5").
The months with the least snowfall are June, July and August (0").

Average snowfall days in September
Jackson, MT

Average snowfall days in September - Jackson, MT
  • Average snowfall days in September: 0.3 days

The month with the highest number of snowfall days is February (12.3 days).
The months with the least snowfall days are June, July and August (0 days).

Average daylight in September /
Average sunshine in September
Jackson, MT

Average daylight in September / Average sunshine in September - Jackson, 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 2min

The month with the most sunshine is July (Average sunshine: 11h and 48min).
The month with the least sunshine is January (Average sunshine: 5h and 6min).

Average sunshine days in September
Jackson, MT

Average sunshine days in September - Jackson, MT
  • Average sunshine days in September: 17.7 days

The month with the most sunshine days is July (19.4 days).
The month with the least sunshine days is April (7.7 days).

Average UV index in September
Jackson, MT

Average UV index in September - Jackson, 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 and December (UV index 1).

Average cloud cover in September
Jackson, MT

Average cloud cover in September - Jackson, MT
  • Average cloud cover in September: 19

The month with the most cloud cover is February (Cloud cover 53).
The month with the least cloud cover is August (Cloud cover 13).

Average visibility in September
Jackson, MT

Average visibility in September - Jackson, MT
  • Average visibility in September: 6mi

The months with the highest visibility are May, June, July, August, September and October (6mi).
The months with the lowest visibility are January, February, March and December (4mi).

Jackson, Montana, USA

Weather forecast for your location

1. Click Locate me button
2. Allow the app to use your location