September weather forecast
Kirby, MT

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Weather in September

The first month of the autumn, September, is still a warm month in Kirby, Montana, with an average temperature fluctuating between 52.7°F (11.5°C) and 74.1°F (23.4°C).

Temperature

Onset of September witnesses a reduction in the average high-temperature, falling from 83.7°F (28.7°C) in August to a still moderately hot 74.1°F (23.4°C). An average minimum temperature of 52.7°F (11.5°C) marks the month of September.

Humidity

The average relative humidity in September is 44%.

Rainfall

In Kirby, in September, it is raining for 8.6 days, with typically 0.83" (21mm) of accumulated precipitation. Throughout the year, there are 127.6 rainfall days, and 14.25" (362mm) of precipitation is accumulated.

Snowfall

Months with snowfall are January through May, September through December. September is the first month it typically snows. Throughout September, in the average 0.2 snowfall days, it receives 0.12" (3mm) of snow. Throughout the year, there are 65.3 snowfall days, and 28.82" (732mm) of snow is accumulated.

Daylight

In Kirby, the average length of the day in September is 12h and 31min.
On the first day of the month, sunrise is at 6:30 am and sunset at 7:44 pm. On the last day of September, sunrise is at 7:05 am and sunset at 6:49 pm MDT.

Sunshine

In Kirby, the average sunshine in September is 10.8h.

UV index

The average daily maximum UV index in September is 4. A UV Index reading of 3 to 5 represents a medium health hazard from exposure to the Sun's UV rays for the average person.
Note: The daily high UV index of 4 during September translates into the following recommendations:
Safety measures are advised. Light-skinned individuals may experience burns in under half an hour. Considering the harmful UV rays from the Sun during midday, it's essential to reduce exposure. For optimum UV protection, wear sun-resistant attire complemented with a hat and quality shades. Beware! The strength of the UV rays is increased nearly double-fold by the reflection of the snow.
Updated: Jul 30, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What are the temperatures in September?

In Kirby, 74.1°F (23.4°C) is the average high-temperature and 52.7°F (11.5°C) is the average low-temperature during September. In August, the average heat index (a.k.a. 'felt air temperature', 'feels like'), which factors the actual air temperature with the relative humidity, is calculated to be 82.4°F (28°C).

What is the average humidity in September?

In September, the average relative humidity is 44%.

How many days does it rain in September?

In Kirby, in September, it is raining for 8.6 days, with typically 0.83" (21mm) of accumulated precipitation.

When does it start to snow?

September is the first month it typically snows. Throughout September, in the average 0.2 snowfall days, it receives 0.12" (3mm) of snow.

What is the average length of the day in September?

In Kirby, Montana, the average day length in September is 12h and 31min.

When is the sunrise / sunset in September?

On the first day of September, sunrise is at 6:30 am and sunset at 7:44 pm. On the last day of the month, sunrise is at 7:05 am and sunset at 6:49 pm MDT.

How many hours of sunshine does Kirby have in September?

In Kirby, the average sunshine duration in September is 10.8h.

How high is the UV index in September?

The average daily maximum UV index in September is 4. A UV Index value of 3 to 5 symbolizes a medium hazard to health 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
Kirby, MT

Average temperature in September - Kirby, MT
  • Average high temperature in September: 74.1°F

The warmest month (with the highest average high temperature) is July (85.5°F).
The month with the lowest average high temperature is December (31.1°F).

  • Average low temperature in September: 52.7°F

The month with the highest average low temperature is July (61.5°F).
The coldest months (with the lowest average low temperature) are January and February (16.2°F).

Average pressure in September
Kirby, MT

Average pressure in September - Kirby, MT
  • Average pressure in September: 29.93"Hg

The month with the highest atmospheric pressure is January (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.85"Hg).

Average wind speed in September
Kirby, MT

Average wind speed in September - Kirby, MT
  • Average wind speed in September: 7.6mph

The windiest month (with the highest average wind speed) is April (9.1mph).
The calmest months (with the lowest average wind speed) are July and December (6.8mph).

Average humidity in September
Kirby, MT

Average humidity in September - Kirby, MT
  • Average humidity in September: 44%

The months with the highest relative humidity are January and February (79%).
The month with the lowest relative humidity is August (40%).

Average rainfall in September
Kirby, MT

Average rainfall in September - Kirby, MT
  • Average rainfall in September: 0.83"

The wettest month (with the highest rainfall) is May (2.64").
The driest month (with the least rainfall) is December (0.67").

Average rainfall days in September
Kirby, MT

Average rainfall days in September - Kirby, MT
  • Average rainfall days in September: 8.6 days

The month with the highest number of rainy days is May (18 days).
The month with the least rainy days is January (6.3 days).

Average snowfall in September
Kirby, MT

Average snowfall in September - Kirby, MT
  • Average snowfall in September: 0.12"

The month with the highest snowfall is February (5.2").
The months with the least snowfall are June, July and August (0").

Average snowfall days in September
Kirby, MT

Average snowfall days in September - Kirby, MT
  • Average snowfall days in September: 0.2 days

The month with the highest number of snowfall days is February (14.3 days).
The months with the least snowfall days are June, July and August (0 days).

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

Average daylight in September / Average sunshine in September - Kirby, 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: 10h and 5min

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: 5h and 42min).

Average sunshine days in September
Kirby, MT

Average sunshine days in September - Kirby, MT
  • Average sunshine days in September: 18.2 days

The month with the most sunshine days is September (18.2 days).
The month with the least sunshine days is May (9.6 days).

Average UV index in September
Kirby, MT

Average UV index in September - Kirby, MT
  • Average UV index in September: 4

The month with the highest UV index is July (UV index 7).
The months with the lowest UV index are January, February, March, November and December (UV index 2).

Average cloud cover in September
Kirby, MT

Average cloud cover in September - Kirby, MT
  • Average cloud cover in September: 18

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 14).

Average visibility in September
Kirby, MT

Average visibility in September - Kirby, 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).

Kirby, Montana, USA

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