September weather forecast
Saint Johns, MT

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Weather in September

The first month of the autumn, September, is still a pleasant month in Saint Johns, Montana, with an average temperature varying between 70.5°F (21.4°C) and 52.5°F (11.4°C).

Temperature

September ushers in a slight temperature change, with average high-temperatures reducing from August's moderately hot 81.3°F (27.4°C) to an agreeable 70.5°F (21.4°C). Saint Johns, during September, witnesses an average low-temperature of 52.5°F (11.4°C).

Humidity

In September, the average relative humidity is 45%.

Rainfall

In September, in Saint Johns, the rain falls for 7.6 days. Throughout September, 0.63" (16mm) of precipitation is accumulated. Throughout the year, in Saint Johns, there are 98.7 rainfall days, and 8.23" (209mm) of precipitation is accumulated.

Snowfall

January through May, September through December are months with snowfall. September is the first month it typically snows in Saint Johns. Throughout September, in the average 0.2 snowfall days, it receives 0.51" (13mm) of snow. Throughout the year, there are 53.5 snowfall days, and 14.25" (362mm) of snow is accumulated.

Daylight

In September, the average length of the day in Saint Johns is 12h and 34min.
On the first day of the month, sunrise is at 6:38 am and sunset at 8:01 pm. On the last day of September, sunrise is at 7:19 am and sunset at 7:00 pm MDT.

Sunshine

The average sunshine in September is 10.1h.

UV index

The average daily maximum UV index in September in Saint Johns is 4. A UV Index estimate of 3 to 5 represents a moderate threat to health from unsafe exposure to UV radiation for ordinary individuals.
Note: A maximum daily UV index of 4 during September morphs into the following directions:
Guard yourself - An obligation to protect skin and eyes from harm exists. Protect yourself from the midday Sun's peak UV radiation by minimizing exposure. Fend off the sun's harsh rays with appropriate clothing, a wide-brim hat, and UV-protective sunglasses. Be on the lookout! Nearly twofold UV radiation from the Sun can be reflected by snow.
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Frequently asked questions

What are the temperatures in Saint Johns in September?

The high-temperature in Saint Johns during September is 70.5°F (21.4°C) and the low-temperature is 52.5°F (11.4°C). In August, the average heat index (a.k.a. 'feels like', 'apparent temperature'), which calculates the temperature value influenced by the moisture in the air, is appraised at 80.6°F (27°C).

What is the average humidity in September in Saint Johns?

In September, the average relative humidity in Saint Johns, Montana, is 45%.

How many days does it rain in September in Saint Johns?

In Saint Johns, in September, during 7.6 rainfall days, 0.63" (16mm) of precipitation is typically accumulated.

When does it start to snow in Saint Johns?

September is the first month it typically snows in Saint Johns. Throughout September, in the average 0.2 snowfall days, it receives 0.51" (13mm) of snow.

What is the average length of the day in September in Saint Johns?

In September, the average day length is 12h and 34min.

When are sunrise and sunset in September in Saint Johns?

In September, on the first day of the month, sunrise is at 6:38 am and sunset at 8:01 pm. On the last day of the month, in Saint Johns, sunrise is at 7:19 am and sunset at 7:00 pm MDT.

How long on average sun shines in September in Saint Johns?

The average sunshine duration in September in Saint Johns is 10.1h.

What is the UV index intensity in September in Saint Johns?

In September, the average daily maximum UV index is 4. A UV Index of 3 to 5 symbolizes a moderate health threat 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
Saint Johns, MT

Average temperature in September - Saint Johns, MT
  • Average high temperature in September: 70.5°F

The warmest month (with the highest average high temperature) is July (82.8°F).
The months with the lowest average high temperature are January and December (27.1°F).

  • Average low temperature in September: 52.5°F

The month with the highest average low temperature is August (61.3°F).
The coldest month (with the lowest average low temperature) is February (13.5°F).

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Average pressure in September
Saint Johns, MT

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

The months with the highest atmospheric pressure are January and February (30.12"Hg).
The month with the lowest atmospheric pressure is June (29.84"Hg).

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Average wind speed in September
Saint Johns, MT

Average wind speed in September - Saint Johns, MT
  • Average wind speed in September: 9mph

The windiest month (with the highest average wind speed) is April (10.6mph).
The calmest month (with the lowest average wind speed) is August (8.5mph).

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Average humidity in September
Saint Johns, MT

Average humidity in September - Saint Johns, MT
  • Average humidity in September: 45%

The month with the highest relative humidity is January (83%).
The month with the lowest relative humidity is August (40%).

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Average rainfall in September
Saint Johns, MT

Average rainfall in September - Saint Johns, MT
  • Average rainfall in September: 0.63"

The wettest month (with the highest rainfall) is June (1.5").
The driest month (with the least rainfall) is December (0.31").

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Average rainfall days in September
Saint Johns, MT

Average rainfall days in September - Saint Johns, MT
  • Average rainfall days in September: 7.6 days

The month with the highest number of rainy days is May (13.8 days).
The month with the least rainy days is February (4 days).

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Average snowfall in September
Saint Johns, MT

Average snowfall in September - Saint Johns, MT
  • Average snowfall in September: 0.51"

The month with the highest snowfall is February (2.72").
The months with the least snowfall are June, July and August (0").

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Average snowfall days in September
Saint Johns, MT

Average snowfall days in September - Saint Johns, MT
  • Average snowfall days in September: 0.2 days

The month with the highest number of snowfall days is February (11 days).
The months with the least snowfall days are June, July and August (0 days).

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Average daylight in September /
Average sunshine in September
Saint Johns, MT

Average daylight in September / Average sunshine in September - Saint Johns, MT
  • Average daylight in September: 12h and 4min

The month with the longest days is June (Average daylight: 16h and 6min).
The month with the shortest days is December (Average daylight: 8h and 18min).

  • Average sunshine in September: 10h and 1min

The month with the most sunshine is July (Average sunshine: 12h and 0min).
The month with the least sunshine is February (Average sunshine: 5h and 18min).

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Average sunshine days in September
Saint Johns, MT

Average sunshine days in September - Saint Johns, MT
  • Average sunshine days in September: 20.3 days

The month with the most sunshine days is September (20.3 days).
The month with the least sunshine days is April (12.8 days).

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Average UV index in September
Saint Johns, MT

Average UV index in September - Saint Johns, MT
  • Average UV index in September: 4

The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January, February, March, October, November and December (UV index 2).

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Average cloud cover in September
Saint Johns, MT

Average cloud cover in September - Saint Johns, MT
  • Average cloud cover in September: 22

The month with the most cloud cover is February (Cloud cover 46).
The months with the least cloud cover are July and August (Cloud cover 16).

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Average visibility in September
Saint Johns, MT

Average visibility in September - Saint Johns, 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).

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Saint Johns, Montana, USA

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