September weather forecast
Fairfield, ID

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Weather in September

September, the first month of the autumn in Fairfield, is still a pleasant month, with an average temperature fluctuating between 70.9°F (21.6°C) and 49.1°F (9.5°C).

Temperature

As September begins, there is a decrease in the average high-temperature, falling from a warm 81.7°F (27.6°C) in August to an agreeable 70.9°F (21.6°C). September nights in Fairfield show a substantial disparity from the daytime peak with an average low-temperature of 49.1°F (9.5°C).

Humidity

In September, the average relative humidity is 39%.

Rainfall

In September, in Fairfield, the rain falls for 6.2 days. Throughout September, 0.43" (11mm) of precipitation is accumulated. Throughout the year, in Fairfield, there are 74.4 rainfall days, and 8.03" (204mm) of precipitation is accumulated.

Snowfall

January through May, September through December are months with snowfall in Fairfield. September is the first month it typically snows in Fairfield, Idaho. Throughout September, in the average 0.2 snowfall days, it receives 0.04" (1mm) of snow. Throughout the year, there are 44.1 snowfall days, and 29.65" (753mm) of snow is accumulated.

Daylight

In Fairfield, the average length of the day in September is 12h and 29min.
On the first day of the month, sunrise is at 7:04 am and sunset at 8:13 pm. On the last day of September, in Fairfield, sunrise is at 7:36 am and sunset at 7:21 pm MDT.

Sunshine

The average sunshine in September is 9.6h.

UV index

In September, the average daily maximum UV index is 4. A UV Index reading of 3 to 5 represents a moderate health risk from exposure to the Sun's UV rays for the ordinary person.
Note: A maximum daily UV index of 4 during September morphs into the following directions:
Take precautions. Light skin individuals may get burned in less than 30 minutes. UV radiation is strongest from the Sun during midday; protect yourself by staying in shaded areas. Experience reduced UV exposure by about half when donning a wide-brim hat. Be attentive! The reflective property of snow can nearly double the Sun's UV radiation.
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Frequently asked questions

What is the average September temperature in Fairfield?

In September, the average high-temperature and low-temperature in Fairfield are 70.9°F (21.6°C) and 49.1°F (9.5°C) respectively.

What is the average humidity in September in Fairfield?

The average relative humidity in September is 39%.

How many days does it rain in September in Fairfield?

In September, in Fairfield, the rain falls for 6.2 days. Throughout September, 0.43" (11mm) of precipitation is accumulated.

When does it start to snow in Fairfield?

September is the first month it typically snows in Fairfield. Throughout September, in the average 0.2 snowfall days, it receives 0.04" (1mm) of snow.

What is the average length of the day in September in Fairfield?

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

When is the sunrise / sunset in September in Fairfield?

On the first day of September, sunrise is at 7:04 am and sunset at 8:13 pm. On the last day of the month, sunrise is at 7:36 am and sunset at 7:21 pm MDT.

How many hours of sunshine does Fairfield have in September?

In September, the average sunshine duration in Fairfield is 9.6h.

How high is the UV index in September in Fairfield?

The average daily maximum UV index in September in Fairfield, Idaho, is 4. A UV Index estimate of 3 to 5 represents a moderate vulnerability from exposure to the Sun's UV radiation.
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
Fairfield, ID

Average temperature in September - Fairfield, ID
  • Average high temperature in September: 70.9°F

The warmest month (with the highest average high temperature) is July (82.9°F).
The month with the lowest average high temperature is December (27.9°F).

  • Average low temperature in September: 49.1°F

The months with the highest average low temperature are July and August (55.6°F).
The coldest month (with the lowest average low temperature) is January (14.4°F).

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Average pressure in September
Fairfield, ID

Average pressure in September - Fairfield, ID
  • Average pressure in September: 29.94"Hg

The month with the highest atmospheric pressure is January (30.28"Hg).
The month with the lowest atmospheric pressure is June (29.88"Hg).

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Average wind speed in September
Fairfield, ID

Average wind speed in September - Fairfield, ID
  • Average wind speed in September: 6.6mph

The windiest months (with the highest average wind speed) are April and June (7.6mph).
The calmest month (with the lowest average wind speed) is December (5.3mph).

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Average humidity in September
Fairfield, ID

Average humidity in September - Fairfield, ID
  • Average humidity in September: 39%

The month with the highest relative humidity is January (84%).
The month with the lowest relative humidity is August (32%).

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Average rainfall in September
Fairfield, ID

Average rainfall in September - Fairfield, ID
  • Average rainfall in September: 0.43"

The wettest month (with the highest rainfall) is February (1.02").
The driest month (with the least rainfall) is July (0.28").

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Average rainfall days in September
Fairfield, ID

Average rainfall days in September - Fairfield, ID
  • Average rainfall days in September: 6.2 days

The month with the highest number of rainy days is May (12 days).
The month with the least rainy days is January (2.8 days).

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Average snowfall in September
Fairfield, ID

Average snowfall in September - Fairfield, ID
  • Average snowfall in September: 0.04"

The month with the highest snowfall is February (7.87").
The months with the least snowfall are June, July and August (0").

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Average snowfall days in September
Fairfield, ID

Average snowfall days in September - Fairfield, ID
  • Average snowfall days in September: 0.2 days

The month with the highest number of snowfall days is December (10.5 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
Fairfield, ID

Average daylight in September / Average sunshine in September - Fairfield, 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 0min).

  • Average sunshine in September: 9h and 4min

The month with the most sunshine is July (Average sunshine: 12h and 0min).
The months with the least sunshine are January and December (Average sunshine: 5h and 54min).

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Average sunshine days in September
Fairfield, ID

Average sunshine days in September - Fairfield, ID
  • Average sunshine days in September: 21.2 days

The month with the most sunshine days is October (23.5 days).
The month with the least sunshine days is May (15.6 days).

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Average UV index in September
Fairfield, ID

Average UV index in September - Fairfield, 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
Fairfield, ID

Average cloud cover in September - Fairfield, ID
  • Average cloud cover in September: 13

The month with the most cloud cover is December (Cloud cover 38).
The month with the least cloud cover is July (Cloud cover 9).

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Average visibility in September
Fairfield, ID

Average visibility in September - Fairfield, 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).

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Fairfield, Idaho, USA

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