Sun Valley
Idaho, USA
Long-term weather forecast
Long-term weather forecast

September weather forecast and climate
Sun Valley, ID

The iconic Sun Valley, Idaho, in a stunning hilly landscape on either side located within the famous White Cloud Wilderness, white clouds above
The iconic Sun Valley, Idaho, in a stunning hilly landscape on either side located within the famous White Cloud Wilderness, white clouds above
The first month of the autumn, September, is still a pleasant month in Sun Valley, Idaho, with temperature in the range of an average high of 72.3°F (22.4°C) and an average low of 29.8°F (-1.2°C).

Temperature

In Sun Valley, the average high-temperature drops, from a moderately hot 81.7°F (27.6°C) in August, to a pleasant 72.3°F (22.4°C). In Sun Valley, in September, the average low-temperature is 29.8°F (-1.2°C).

Rainfall

In Sun Valley, during September, the rain falls for 8 days and regularly aggregates up to 0.9" (22.6mm) of precipitation. In Sun Valley, during the entire year, the rain falls for 122 days and collects up to 17.2" (438.1mm) of precipitation.

Snowfall

January through May, September through December are months with snowfall.

Daylight

The average length of the day in Sun Valley is 12.5h.

Sunshine

In September, the average sunshine in Sun Valley is 9h.

UV index

In September, the average daily maximum UV index is 6. A UV Index estimate of 6 to 7 represents a high health hazard from the exposure to the Sun's UV rays for average individuals.
In September, the average maximum UV index of 6 translate into the following recommendations:
Take precautions against overexposure. Protection against sun damage is needed. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. 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. Beware! The strength of the UV rays is increased nearly double-fold by the reflection of the snow.

What is the temperature in September in Sun Valley?

The average high-temperature, in September, is 72.3°F (22.4°C), while the average low-temperature is 29.8°F (-1.2°C).

How many days does it rain in September in Sun Valley?

In Sun Valley, during September, the rain falls for 8 days and regularly aggregates up to 0.9" (22.6mm) of precipitation.

When does it start snowing in Sun Valley?

September is the first month it typically snows in Sun Valley. Throughout September, Sun Valley receives 0.5" (12.7mm) of snow.

How many hours of daylight does Sun Valley have in September?

In Sun Valley, Idaho, the average length of the day in September is 12.5h.

How many hours of sunshine does Sun Valley have in September?

The average sunshine in September in Sun Valley is 9h.

What is the UV index intensity in September in Sun Valley?

In Sun Valley, Idaho, the average daily maximum UV index in September is 6. A UV Index of 6 to 7 symbolizes a high health risk from unsafe exposure to the Sun's UV rays.
Average temperature in September - Sun Valley, ID
  • Average high temperature in September: 72.3°F

The warmest month (with the highest average high temperature) is July (82.5°F).
The month with the lowest average high temperature is January (30°F).

  • Average low temperature in September: 29.9°F

The month with the highest average low temperature is July (38.3°F).
The coldest month (with the lowest average low temperature) is January (0.3°F).

Average rainfall in September - Sun Valley, ID
  • Average rainfall in September: 0.9"

Wettest months (with the highest rainfall) are January and December (2.6").
The driest month (with the lowest rainfall) is July (0.7").

Average rainfall days in September - Sun Valley, ID
  • Average rainfall days in September: 8 days

Months with the highest number of rainy days are January, March and December (13 days).
Months with the lowest number of rainy days are July and October (7 days).

Average snowfall in September - Sun Valley, ID
  • Average snowfall in September: 0.5"

The month with the highest snowfall is January (36").
Months with the lowest snowfall are June, July and August (0").

Average daylight in September / Average sunshine in September - Sun Valley, ID
  • Average daylight in September: 12.5h

The month with the longest days is June (Average daylight: 15.4h).
The month with shortest days is December (Average daylight: 9h).

  • Average sunshine in September: 9h

The month with most sunshine is July (Average sunshine: 12h).
Months with least sunshine are January, November and December (Average sunshine: 4).

Average UV index in September - Sun Valley, ID
  • Average UV index in September: 6

The month with the highest UV index is July (UV index 10).
The month with the lowest UV index is December (UV index 1).