September weather forecast
American Falls, ID

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Weather in September

September in American Falls brings a gradual transition towards cooler autumn weather. A notable dip in temperatures underscores the shift away from the summer season. The increased cloudiness reflects the slowly dipping temperature levels. Slight variations can be observed in other climatological parameters, including a slight increase in wind speed. Favorably, the rainfall averages none too high, holding at a steady 0.75" (19mm) for the month.

Temperature

American Falls experiences a temperature shift at the start of September, with average high-temperatures adjusting from 84.4°F (29.1°C) in August to a still moderately hot 73.9°F (23.3°C). During September, American Falls's temperature records a considerable difference from its daily highs to an average low of 51.8°F (11°C).

Humidity

In September, the average relative humidity in American Falls is 38%.

Rainfall

In September, the rain falls for 8.2 days. Throughout September, 0.75" (19mm) of precipitation is accumulated. Throughout the year, there are 108.7 rainfall days, and 10.47" (266mm) of precipitation is accumulated.

Snowfall

January through May, September through December are months with snowfall. September is the first month it typically snows in American Falls. Throughout September, in the average 0.2 snowfall days, it receives 0.39" (10mm) of snow. Throughout the year, there are 57.1 snowfall days, and 25.2" (640mm) of snow is accumulated.

Daylight

The average length of the day in September in American Falls, Idaho, is 12h and 28min.
On the first day of the month, sunrise is at 6:57 am and sunset at 8:05 pm. On the last day of September, sunrise is at 7:28 am and sunset at 7:13 pm MDT.

Sunshine

In American Falls, the average sunshine in September is 9.8h.

UV index

In September, the average daily maximum UV index is 4. A UV Index reading of 3 to 5 represents a moderate threat to health from unprotected exposure to Sun's UV rays for the ordinary person.
Note: The average daily UV index of 4 in September transforms into the following instructions:
Undertake protective steps - Preventing sun damage is advised. It's recommended to limit sun exposure when its radiation is at its peak during midday. Counter UV radiation's ill effects with clothing designed for sun safety and UV-resistant eyewear. Take careful note! The UV radiation of the Sun can be nearly doubled by snow reflection.
Updated: Feb 12, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the usual temperature for American Falls in September?

During September, American Falls experiences an average high-temperature of 73.9°F (23.3°C) and a low-temperature of 51.8°F (11°C).

What is the average humidity in September in American Falls?

In September, the average relative humidity is 38%.

How much does it rain in American Falls in September?

In American Falls, Idaho, in September, it is raining for 8.2 days, with typically 0.75" (19mm) of accumulated precipitation.

When does it start to snow in American Falls?

September is the first month it typically snows in American Falls, Idaho. Throughout September, in the average 0.2 snowfall days, it receives 0.39" (10mm) of snow.

What is the average length of the day in September in American Falls?

The average day length in September in American Falls is 12h and 28min.

What time are sunrise and sunset in September in American Falls?

On the first day of September in American Falls, Idaho, sunrise is at 6:57 am and sunset at 8:05 pm. On the last day of the month, sunrise is at 7:28 am and sunset at 7:13 pm MDT.

How many hours of sunshine does American Falls have in September?

In September, the average sunshine duration is 9.8h.

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

In American Falls, Idaho, the average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a medium health risk from exposure to Sun's UV rays.
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
American Falls, ID

Average temperature in September - American Falls, ID
  • Average high temperature in September: 73.9°F

The warmest month (with the highest average high temperature) is July (85.8°F).
The month with the lowest average high temperature is December (29.3°F).

  • Average low temperature in September: 51.8°F

The month with the highest average low temperature is August (58.5°F).
The coldest months (with the lowest average low temperature) are January and December (18°F).

Average pressure in September
American Falls, ID

Average pressure in September - American Falls, ID
  • Average pressure in September: 29.96"Hg

The month with the highest atmospheric pressure is January (30.3"Hg).
The month with the lowest atmospheric pressure is June (29.89"Hg).

Average wind speed in September
American Falls, ID

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

The windiest month (with the highest average wind speed) is April (9.6mph).
The calmest months (with the lowest average wind speed) are January and December (7mph).

Average humidity in September
American Falls, ID

Average humidity in September - American Falls, ID
  • Average humidity in September: 38%

The month with the highest relative humidity is January (86%).
The month with the lowest relative humidity is August (32%).

Average rainfall in September
American Falls, ID

Average rainfall in September - American Falls, ID
  • Average rainfall in September: 0.75"

The wettest month (with the highest rainfall) is March (1.18").
The driest month (with the least rainfall) is July (0.59").

Average rainfall days in September
American Falls, ID

Average rainfall days in September - American Falls, ID
  • Average rainfall days in September: 8.2 days

The month with the highest number of rainy days is March (12.5 days).
The month with the least rainy days is January (6.4 days).

Average snowfall in September
American Falls, ID

Average snowfall in September - American Falls, ID
  • Average snowfall in September: 0.39"

The month with the highest snowfall is January (7.2").
The months with the least snowfall are June, July and August (0").

Average snowfall days in September
American Falls, ID

Average snowfall days in September - American Falls, ID
  • Average snowfall days in September: 0.2 days

The month with the highest number of snowfall days is December (13.7 days).
The months with the least snowfall days are July and August (0 days).

Average daylight in September /
Average sunshine in September
American Falls, ID

Average daylight in September / Average sunshine in September - American Falls, ID
  • Average daylight in September: 12h and 3min

The month with the longest days is June (Average daylight: 15h and 18min).
The month with the shortest days is December (Average daylight: 9h and 6min).

  • Average sunshine in September: 9h and 5min

The months with the most sunshine are June and July (Average sunshine: 11h and 54min).
The month with the least sunshine is January (Average sunshine: 5h and 6min).

Average sunshine days in September
American Falls, ID

Average sunshine days in September - American Falls, ID
  • Average sunshine days in September: 19.3 days

The month with the most sunshine days is October (20.3 days).
The month with the least sunshine days is February (12.4 days).

Average UV index in September
American Falls, ID

Average UV index in September - American Falls, ID
  • Average UV index in September: 4

The months with the highest UV index are June and July (UV index 6).
The month with the lowest UV index is December (UV index 1).

Average cloud cover in September
American Falls, ID

Average cloud cover in September - American Falls, ID
  • Average cloud cover in September: 15

The months with the most cloud cover are February and December (Cloud cover 47).
The months with the least cloud cover are July and August (Cloud cover 11).

Average visibility in September
American Falls, ID

Average visibility in September - American 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, February and December (5mi).

American Falls, Idaho, USA

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