September weather forecast
Irwin, ID

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Weather in September

September, the first month of the autumn in Irwin, is still a refreshing month, with temperature in the range of an average low of 40.1°F (4.5°C) and an average high of 66.6°F (19.2°C).

Temperature

The beginning of September marks a decrease in the average high-temperature, transitioning from a moderately hot 76.5°F (24.7°C) in August to a refreshing 66.6°F (19.2°C). In September, the temperature in Irwin sees a substantial plunge from daytime highs to a low average of 40.1°F (4.5°C).

Humidity

The average relative humidity in September in Irwin is 53%.

Rainfall

In Irwin, Idaho, during September, the rain falls for 11.1 days and regularly aggregates up to 1.46" (37mm) of precipitation. Throughout the year, there are 127 rainfall days, and 24.29" (617mm) of precipitation is accumulated.

Snowfall

January through June, September through December are months with snowfall in Irwin, Idaho. September is the first month it typically snows in Irwin. Throughout September, in the average 0.5 snowfall days, it receives 0.47" (12mm) of snow. Throughout the year, in Irwin, there are 126.6 snowfall days, and 110.28" (2801mm) of snow is accumulated.

Daylight

In Irwin, the average length of the day in September is 12h and 29min.
On the first day of September, sunrise is at 6:50 am and sunset at 7:59 pm. On the last day of the month, sunrise is at 7:22 am and sunset at 7:07 pm MDT.

Sunshine

In Irwin, the average sunshine in September is 10.1h.

UV index

In September, the average daily maximum UV index in Irwin is 3. A UV Index reading of 3 to 5 represents a medium health hazard from exposure to the Sun's UV rays for the ordinary person.
Note: A daily high UV index of 3 in September leads to these guidelines:
Be careful. Light complexion individuals might get burns in fewer than 30 minutes. When the Sun's UV radiation is most intense during midday, it's best to find shade and limit exposure. Employ a hat with a wide brim for robust protection, cutting UV exposure by half. Notice this! Nearly double the intensity of the Sun's UV radiation can be caused by snow reflection.
Updated: Feb 12, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What are September temperatures in Irwin?

The average high-temperature, in September, in Irwin, is 66.6°F (19.2°C), while the average low-temperature is 40.1°F (4.5°C).

What is the average humidity in September in Irwin?

The average relative humidity in September is 53%.

How much does it rain in Irwin in September?

In September, the rain falls for 11.1 days. Throughout September, 1.46" (37mm) of precipitation is accumulated.

When does it start to snow in Irwin?

September is the first month it typically snows in Irwin. Throughout September, in the average 0.5 snowfall days, it receives 0.47" (12mm) of snow.

How many hours of daylight does Irwin have in September?

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

When are sunrise and sunset in September in Irwin?

In September, on the first day of the month, sunrise is at 6:50 am and sunset at 7:59 pm. On the last day of the month, sunrise is at 7:22 am and sunset at 7:07 pm MDT.

How many hours of sunshine does Irwin have in September?

In Irwin, Idaho, the average sunshine duration in September is 10.1h.

What is the UV index reading in September in Irwin?

In Irwin, 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 unsafe 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
Irwin, ID

Average temperature in September - Irwin, ID
  • Average high temperature in September: 66.6°F

The warmest month (with the highest average high temperature) is July (77.5°F).
The month with the lowest average high temperature is December (24.3°F).

  • Average low temperature in September: 40.1°F

The months with the highest average low temperature are July and August (45.3°F).
The coldest month (with the lowest average low temperature) is January (7.3°F).

Average pressure in September
Irwin, ID

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

The month with the highest atmospheric pressure is January (30.28"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).

Average wind speed in September
Irwin, ID

Average wind speed in September - Irwin, ID
  • Average wind speed in September: 5.2mph

The windiest month (with the highest average wind speed) is June (5.7mph).
The calmest month (with the lowest average wind speed) is January (4.3mph).

Average humidity in September
Irwin, ID

Average humidity in September - Irwin, ID
  • Average humidity in September: 53%

The month with the highest relative humidity is February (94%).
The month with the lowest relative humidity is August (46%).

Average rainfall in September
Irwin, ID

Average rainfall in September - Irwin, ID
  • Average rainfall in September: 1.46"

The wettest month (with the highest rainfall) is February (2.91").
The driest month (with the least rainfall) is July (0.91").

Average rainfall days in September
Irwin, ID

Average rainfall days in September - Irwin, ID
  • Average rainfall days in September: 11.1 days

The month with the highest number of rainy days is May (17.9 days).
The month with the least rainy days is January (4.6 days).

Average snowfall in September
Irwin, ID

Average snowfall in September - Irwin, ID
  • Average snowfall in September: 0.47"

The month with the highest snowfall is February (22.91").
The months with the least snowfall are July and August (0").

Average snowfall days in September
Irwin, ID

Average snowfall days in September - Irwin, ID
  • Average snowfall days in September: 0.5 days

The months with the highest number of snowfall days are February and December (22.3 days).
The months with the least snowfall days are July and August (0 days).

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

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

The month with the longest days is June (Average daylight: 15h and 24min).
The month with the shortest days is December (Average daylight: 9h and 0min).

  • Average sunshine in September: 10h and 1min

The month with the most sunshine is July (Average sunshine: 11h and 54min).
The month with the least sunshine is February (Average sunshine: 4h and 0min).

Average sunshine days in September
Irwin, ID

Average sunshine days in September - Irwin, ID
  • Average sunshine days in September: 16.2 days

The month with the most sunshine days is September (16.2 days).
The month with the least sunshine days is April (5.3 days).

Average UV index in September
Irwin, ID

Average UV index in September - Irwin, 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, March, November and December (UV index 1).

Average cloud cover in September
Irwin, ID

Average cloud cover in September - Irwin, ID
  • Average cloud cover in September: 18

The month with the most cloud cover is February (Cloud cover 67).
The months with the least cloud cover are July and August (Cloud cover 13).

Average visibility in September
Irwin, ID

Average visibility in September - Irwin, 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 and December (3mi).

Irwin, Idaho, USA

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