September weather forecast
Greycliff, MT

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Weather in September

September, the first month of the autumn in Greycliff, is still a comfortable month, with an average temperature varying between 45.3°F (7.4°C) and 66.7°F (19.3°C).

Temperature

The transition into September involves a decrease in the average high-temperature, falling from a warm 76.6°F (24.8°C) in August to an enjoyable 66.7°F (19.3°C). In Greycliff, September's nights observe an average temperature dip to a frosty 45.3°F (7.4°C).

Humidity

In September, the average relative humidity is 51%.

Rainfall

In September, in Greycliff, the rain falls for 9.8 days. Throughout September, 1.1" (28mm) of precipitation is accumulated. In Greycliff, during the entire year, the rain falls for 129.6 days and collects up to 15.83" (402mm) of precipitation.

Snowfall

Months with snowfall are January through May, September through December. September is the first month it typically snows in Greycliff. Throughout September, in the average 1 snowfall days, it receives 0.51" (13mm) of snow. Throughout the year, in Greycliff, there are 67.6 snowfall days, and 38.19" (970mm) of snow is accumulated.

Daylight

In September, the average length of the day in Greycliff is 12h and 31min.
On the first day of the month, sunrise is at 6:41 am and sunset at 7:56 pm. On the last day of September, sunrise is at 7:17 am and sunset at 7:00 pm MDT.

Sunshine

In September, the average sunshine is 10.2h.

UV index

The average daily maximum UV index in September in Greycliff is 3. A UV Index of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV radiation for the average person.
Note: The daily high UV index of 3 during September translates into the following recommendations:
Take measures. Individuals with light skin might experience burns in under 30 minutes. For skin protection, it's recommended to minimize Sun exposure during its peak hours around midday. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. Remember this! The UV radiation of the Sun can be nearly doubled by the reflective properties of snow.
Updated: Feb 13, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the average September temperature in Greycliff?

September temperatures in Greycliff vary between a high-temperature of 66.7°F (19.3°C) and a low-temperature of 45.3°F (7.4°C).

What is the average humidity in September in Greycliff?

The average relative humidity in September in Greycliff is 51%.

How many days does it rain in September in Greycliff?

In Greycliff, in September, it is raining for 9.8 days, with typically 1.1" (28mm) of accumulated precipitation.

When does it start snowing in Greycliff?

September is the first month it typically snows. Throughout September, in the average 1 snowfall days, it receives 0.51" (13mm) of snow.

What is the average length of the day in September in Greycliff?

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

What time are sunrise and sunset in September in Greycliff?

On the first day of September in Greycliff, sunrise is at 6:41 am and sunset at 7:56 pm. On the last day of the month, sunrise is at 7:17 am and sunset at 7:00 pm MDT.

How many hours of sunshine does Greycliff have in September?

In September, the average sunshine duration in Greycliff is 10.2h.

What is the UV index intensity in September in Greycliff?

In September, the average daily maximum UV index in Greycliff, Montana, is 3. A UV Index value of 3 to 5 symbolizes a moderate vulnerability from exposure to the Sun's 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
Greycliff, MT

Average temperature in September - Greycliff, MT
  • Average high temperature in September: 66.7°F

The warmest month (with the highest average high temperature) is July (78.6°F).
The month with the lowest average high temperature is December (28.4°F).

  • Average low temperature in September: 45.3°F

The month with the highest average low temperature is August (52.9°F).
The coldest month (with the lowest average low temperature) is February (15.3°F).

Average pressure in September
Greycliff, MT

Average pressure in September - Greycliff, MT
  • Average pressure in September: 29.96"Hg

The months with the highest atmospheric pressure are January and December (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.88"Hg).

Average wind speed in September
Greycliff, MT

Average wind speed in September - Greycliff, MT
  • Average wind speed in September: 6.9mph

The windiest month (with the highest average wind speed) is January (11.1mph).
The calmest month (with the lowest average wind speed) is July (5.9mph).

Average humidity in September
Greycliff, MT

Average humidity in September - Greycliff, MT
  • Average humidity in September: 51%

The month with the highest relative humidity is February (80%).
The month with the lowest relative humidity is August (47%).

Average rainfall in September
Greycliff, MT

Average rainfall in September - Greycliff, MT
  • Average rainfall in September: 1.1"

The wettest month (with the highest rainfall) is May (3.15").
The driest month (with the least rainfall) is January (0.47").

Average rainfall days in September
Greycliff, MT

Average rainfall days in September - Greycliff, MT
  • Average rainfall days in September: 9.8 days

The month with the highest number of rainy days is May (19.8 days).
The months with the least rainy days are January and December (5.3 days).

Average snowfall in September
Greycliff, MT

Average snowfall in September - Greycliff, MT
  • Average snowfall in September: 0.51"

The month with the highest snowfall is March (7.09").
The months with the least snowfall are June, July and August (0").

Average snowfall days in September
Greycliff, MT

Average snowfall days in September - Greycliff, MT
  • Average snowfall days in September: 1 days

The month with the highest number of snowfall days is February (12.9 days).
The months with the least snowfall days are June, July and August (0 days).

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

Average daylight in September / Average sunshine in September - Greycliff, MT
  • Average daylight in September: 12h and 3min

The month with the longest days is June (Average daylight: 15h and 42min).
The month with the shortest days is December (Average daylight: 8h and 42min).

  • Average sunshine in September: 10h and 1min

The month with the most sunshine is July (Average sunshine: 11h and 48min).
The months with the least sunshine are January, February and December (Average sunshine: 6h and 12min).

Average sunshine days in September
Greycliff, MT

Average sunshine days in September - Greycliff, MT
  • Average sunshine days in September: 17.8 days

The month with the most sunshine days is January (19.8 days).
The month with the least sunshine days is May (7.7 days).

Average UV index in September
Greycliff, MT

Average UV index in September - Greycliff, MT
  • Average UV index in September: 3

The month with the highest UV index is July (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
Greycliff, MT

Average cloud cover in September - Greycliff, MT
  • Average cloud cover in September: 21

The month with the most cloud cover is February (Cloud cover 41).
The months with the least cloud cover are July and August (Cloud cover 16).

Average visibility in September
Greycliff, MT

Average visibility in September - Greycliff, MT
  • 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).

Greycliff, Montana, USA

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