September weather forecast
Idaho Falls, ID

An eye-catching shot of the Snake River, Idaho Falls, with a view of the iconic Idaho Falls Temple in the back
An eye-catching shot of the Snake River, Idaho Falls, with a view of the iconic Idaho Falls Temple in the back

Weather in September

September, the first month of the autumn in Idaho Falls, is also a moderately hot month, with an average temperature fluctuating between 73.6°F (23.1°C) and 49.5°F (9.7°C).

Temperature

In Idaho Falls, the average high-temperature in September decreases from a warm 84.4°F (29.1°C) in August to a still moderately hot 73.6°F (23.1°C). In September, in Idaho Falls, Idaho, the average low-temperature is 49.5°F (9.7°C).

Humidity

In September, the average relative humidity in Idaho Falls is 41%.

Rainfall

The wettest months are May and September, with an average 0.83" (21mm) of rainfall.

Snowfall

January through May, September through December are months with snowfall in Idaho Falls. September is the first month it typically snows. Throughout September, in the average 0.1 snowfall days, it receives 0.04" (1mm) of snow. In Idaho Falls, during the entire year, snow falls for 54.4 days and aggregates up to 16.89" (429mm) of snow.

Daylight

In Idaho Falls, the average length of the day in September is 12h and 29min.
On the first day of September, sunrise is at 6:52 am and sunset at 8:03 pm. On the last day of the month, sunrise is at 7:24 am and sunset at 7:11 pm MDT.

Sunshine

In September, the average sunshine is 10h.

UV index

In Idaho Falls, the average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a moderate health risk from unprotected exposure to Sun's UV rays for average individuals.
Note: The daily maximum UV index of 4 in September interpret into the following advice:
Take precautions - Protection against skin and eye damage is obliged. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects. Beware! The strength of the UV rays is increased nearly double-fold by the reflection of the snow.
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FAQ

What is the average humidity in September in Idaho Falls?

In September, the average relative humidity is 41%.

What is the wettest month in Idaho Falls?

The wettest months in Idaho Falls, Idaho, are May and September, with an average 0.83" (21mm) of rainfall.

How many days does it rain in September in Idaho Falls?

In Idaho Falls, in September, during 8.1 rainfall days, 0.83" (21mm) of precipitation is typically accumulated.

When does it start snowing in Idaho Falls?

September is the first month it typically snows in Idaho Falls, Idaho. Throughout September, in the average 0.1 snowfall days, it receives 0.04" (1mm) of snow.

How many hours of daylight does Idaho Falls have in September?

In September, the average day length in Idaho Falls, Idaho, is 12h and 29min.

When are sunrise and sunset in September in Idaho Falls?

In September, on the first day of the month, sunrise is at 6:52 am and sunset at 8:03 pm. On the last day of the month, in Idaho Falls, sunrise is at 7:24 am and sunset at 7:11 pm MDT.

How long on average sun shines in September in Idaho Falls?

In Idaho Falls, Idaho, the average sunshine duration in September is 10h.

How high is the UV index in September in Idaho Falls?

The average daily maximum UV index in September in Idaho Falls is 4. A UV Index reading of 3 to 5 represents a moderate vulnerability from unsafe exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Idaho Falls, ID

Average temperature in September - Idaho Falls, ID
  • Average high temperature in September: 73.6°F

The warmest month (with the highest average high temperature) is July (86.2°F).
The month with the lowest average high temperature is December (27.9°F).

  • Average low temperature in September: 49.5°F

The month with the highest average low temperature is August (54.3°F).
The coldest month (with the lowest average low temperature) is January (14.2°F).

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Average pressure in September
Idaho Falls, ID

Average pressure in September - Idaho Falls, ID
  • Average pressure in September: 29.98"Hg

The month with the highest atmospheric pressure is January (30.3"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).

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Average wind speed in September
Idaho Falls, ID

Average wind speed in September - Idaho Falls, ID
  • Average wind speed in September: 7.6mph

The windiest month (with the highest average wind speed) is April (9mph).
The calmest month (with the lowest average wind speed) is January (5.8mph).

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Average humidity in September
Idaho Falls, ID

Average humidity in September - Idaho Falls, ID
  • Average humidity in September: 41%

The month with the highest relative humidity is January (90%).
The month with the lowest relative humidity is August (35%).

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Average rainfall in September
Idaho Falls, ID

Average rainfall in September - Idaho Falls, ID
  • Average rainfall in September: 0.83"

The wettest months (with the highest rainfall) are May and September (0.83").
The driest month (with the least rainfall) is July (0.35").

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Average rainfall days in September
Idaho Falls, ID

Average rainfall days in September - Idaho Falls, ID
  • Average rainfall days in September: 8.1 days

The month with the highest number of rainy days is May (10.7 days).
The month with the least rainy days is January (3.7 days).

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Average snowfall in September
Idaho Falls, ID

Average snowfall in September - Idaho Falls, ID
  • Average snowfall in September: 0.04"

The month with the highest snowfall is January (3.86").
The months with the least snowfall are June, July and August (0").

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Average snowfall days in September
Idaho Falls, ID

Average snowfall days in September - Idaho Falls, ID
  • Average snowfall days in September: 0.1 days

The month with the highest number of snowfall days is December (12.9 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
Idaho Falls, ID

Average daylight in September / Average sunshine in September - Idaho Falls, ID
  • Average daylight in September: 12h and 29min

The month with the longest days is June (Average daylight: 15h and 22min).
The month with the shortest days is December (Average daylight: 9h and 1min).

  • Average sunshine in September: 10h and 0min

The month with the most sunshine is July (Average sunshine: 11h and 48min).
The month with the least sunshine is January (Average sunshine: 4h and 42min).

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Average sunshine days in September
Idaho Falls, ID

Average sunshine days in September - Idaho Falls, ID
  • Average sunshine days in September: 19.4 days

The month with the most sunshine days is October (22.1 days).
The month with the least sunshine days is February (16.2 days).

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Average UV index in September
Idaho Falls, ID

Average UV index in September - Idaho Falls, ID
  • 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
Idaho Falls, ID

Average cloud cover in September - Idaho Falls, ID
  • Average cloud cover in September: 16

The months with the most cloud cover are January and February (Cloud cover 51).
The months with the least cloud cover are July and August (Cloud cover 11).

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Average visibility in September
Idaho Falls, ID

Average visibility in September - Idaho Falls, ID
  • 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 and February (4mi).

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