September weather forecast
Salmon, ID

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Bright yellow trees along the shores of the iconic Salmon River in Salmon, Idaho
Bright yellow trees along the shores of the iconic Salmon River in Salmon, Idaho

Weather in September

September is synonymous with the arrival of fall in Salmon, featuring a transition from warm, sunny days to cool, crisp nights. The majestic fall foliage together with the cooling temperatures make it an inviting month for outdoor activities. The month brings noteworthy changes in the weather parameters, the temperature sees a drop to 65.3°F (18.5°C). The city bids goodbye to summer heat and gradually embraces the cool nip in the air. Residents and visitors alike can experience the poetic melancholy of autumn in September's weather.

Temperature

The shift from August to September in Salmon involves a decrease in the average high-temperature, dropping from a moderately hot 74.7°F (23.7°C) to a comfortable 65.3°F (18.5°C). Salmon receives a consistent average low-temperature of 40.6°F (4.8°C) in September, a substantial dip from the day's heat.

Humidity

In Salmon, the average relative humidity in September is 50%.

Rainfall

In Salmon, during September, the rain falls for 9.4 days and regularly aggregates up to 0.94" (24mm) of precipitation. Throughout the year, there are 129.5 rainfall days, and 12.4" (315mm) of precipitation is accumulated.

Snowfall

January through May, September through December are months with snowfall. September is the first month it typically snows. Throughout September, in the average 0.3 snowfall days, it receives 0.43" (11mm) of snow. In Salmon, during the entire year, snow falls for 63.5 days and aggregates up to 22.76" (578mm) of snow.

Daylight

The average length of the day in September is 12h and 31min.
On the first day of September, sunrise is at 6:58 am and sunset at 8:12 pm. On the last day of the month, sunrise is at 7:33 am and sunset at 7:17 pm MDT.

Sunshine

In September, the average sunshine is 9.4h.

UV index

In September, the average daily maximum UV index is 3. A UV Index reading of 3 to 5 represents a moderate threat to health from exposure to the Sun's UV radiation for ordinary individuals.
Note: The daily maximum UV index of 3 in September interprets into the following advice:
Prioritize safety - Suggestions to prevent sun damage are offered. Solar radiation is at its peak intensity during midday, so it's advisable to stay indoors or in the shade. Tightly woven clothing, when worn loosely, shields effectively against the Sun. Note well! The intensity of the Sun's UV rays can be nearly doubled by snow reflection.
Updated: Jul 20, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the temperature in September?

September temperatures vary between a high-temperature of 65.3°F (18.5°C) and a low-temperature of 40.6°F (4.8°C).

What is the average humidity in September?

In Salmon, the average relative humidity in September is 50%.

How much does it rain in September?

In Salmon, in September, during 9.4 rainfall days, 0.94" (24mm) of precipitation is typically accumulated.

When does it start snowing?

September is the first month it typically snows. Throughout September, in the average 0.3 snowfall days, it receives 0.43" (11mm) of snow.

What is the average length of the day in September?

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

When is the sunrise / sunset in September?

On the first day of September, sunrise is at 6:58 am and sunset at 8:12 pm. On the last day of the month, sunrise is at 7:33 am and sunset at 7:17 pm MDT.

How many hours of sunshine does Salmon have in September?

The average sunshine duration in September is 9.4h.

What is the UV index reading in September?

In Salmon, the average daily maximum UV index in September is 3. A UV Index estimate of 3 to 5 represents a medium hazard to health 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
Salmon, ID

Average temperature in September - Salmon, ID
  • Average high temperature in September: 65.3°F

The warmest month (with the highest average high temperature) is July (75.7°F).
The month with the lowest average high temperature is December (25.2°F).

  • Average low temperature in September: 40.6°F

The month with the highest average low temperature is August (47.5°F).
The coldest months (with the lowest average low temperature) are January and December (9.5°F).

Average pressure in September
Salmon, ID

Average pressure in September - Salmon, ID
  • Average pressure in September: 29.99"Hg

The month with the highest atmospheric pressure is January (30.25"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).

Average wind speed in September
Salmon, ID

Average wind speed in September - Salmon, ID
  • Average wind speed in September: 4.5mph

The windiest months (with the highest average wind speed) are March and April (5.2mph).
The calmest month (with the lowest average wind speed) is August (4.3mph).

Average humidity in September
Salmon, ID

Average humidity in September - Salmon, ID
  • Average humidity in September: 50%

The month with the highest relative humidity is February (89%).
The month with the lowest relative humidity is August (43%).

Average rainfall in September
Salmon, ID

Average rainfall in September - Salmon, ID
  • Average rainfall in September: 0.94"

The wettest month (with the highest rainfall) is June (2.05").
The driest months (with the least rainfall) are July and August (0.51").

Average rainfall days in September
Salmon, ID

Average rainfall days in September - Salmon, ID
  • Average rainfall days in September: 9.4 days

The month with the highest number of rainy days is May (18.3 days).
The month with the least rainy days is January (6.3 days).

Average snowfall in September
Salmon, ID

Average snowfall in September - Salmon, ID
  • Average snowfall in September: 0.43"

The month with the highest snowfall is February (5").
The months with the least snowfall are June, July and August (0").

Average snowfall days in September
Salmon, ID

Average snowfall days in September - Salmon, ID
  • Average snowfall days in September: 0.3 days

The month with the highest number of snowfall days is February (12.3 days).
The months with the least snowfall days are June, July and August (0 days).

Average daylight in September /
Average sunshine in September
Salmon, ID

Average daylight in September / Average sunshine in September - Salmon, ID
  • 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: 9h and 2min

The month with the most sunshine is July (Average sunshine: 11h and 48min).
The month with the least sunshine is January (Average sunshine: 5h and 6min).

Average sunshine days in September
Salmon, ID

Average sunshine days in September - Salmon, ID
  • Average sunshine days in September: 17.7 days

The month with the most sunshine days is July (19.4 days).
The month with the least sunshine days is April (7.7 days).

Average UV index in September
Salmon, ID

Average UV index in September - Salmon, ID
  • Average UV index in September: 3

The month with the highest UV index is July (UV index 5).
The months with the lowest UV index are January, February and December (UV index 1).

Average cloud cover in September
Salmon, ID

Average cloud cover in September - Salmon, ID
  • Average cloud cover in September: 19

The month with the most cloud cover is February (Cloud cover 53).
The month with the least cloud cover is August (Cloud cover 13).

Average visibility in September
Salmon, ID

Average visibility in September - Salmon, ID
  • Average visibility in September: 6mi

The months with the highest visibility are May, June, July, August, September and October (6mi).
The months with the lowest visibility are January, February, March and December (4mi).

Salmon, Idaho, USA

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