September weather forecast
Evanston, WY

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Weather in September

September in Evanston marks the arrival of fall, with a noticeable drop in temperature compared to August's highs. The weather changes remarkably, with snowfall figures rising back to 0.91" (23mm) from August's nearly non-existent totals. September ushers in fall's colourful spectacle, with leaves changing from green to shades of gold, and orange, providing photogenic landscapes. September's weather heralds the onset of cooler days, with October expected to introduce much colder temperatures.

Temperature

As August transitions into September, Evanston sees a drop in the average high-temperature, transitioning from a warm 77.5°F (25.3°C) to an agreeable 68.5°F (20.3°C). Evanston records a pronounced decline from the day's peak to an average nighttime low-temperature of 45°F (7.2°C) throughout September.

Humidity

In September, the average relative humidity in Evanston is 44%.

Rainfall

In Evanston, in September, it is raining for 8 days, with typically 0.71" (18mm) of accumulated precipitation. In Evanston, during the entire year, the rain falls for 94.2 days and collects up to 11.5" (292mm) of precipitation.

Snowfall

Months with snowfall in Evanston, Wyoming, are January through June, September through December. September is the first month it typically snows in Evanston. Throughout September, in the average 1.1 snowfall days, it receives 0.91" (23mm) of snow. In Evanston, during the entire year, snow falls for 99.3 days and aggregates up to 56.22" (1428mm) of snow.

Daylight

In Evanston, the average length of the day in September is 12h and 27min.
On the first day of September in Evanston, sunrise is at 6:51 am and sunset at 7:56 pm. On the last day of the month, sunrise is at 7:20 am and sunset at 7:06 pm MDT.

Sunshine

The average sunshine in September in Evanston is 10.3h.

UV index

The average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a medium vulnerability from exposure to the Sun's UV rays for ordinary individuals.
Note: The daily high UV index of 4 during September translates into the following recommendations:
Be mindful. Those with pale skin might receive burns in fewer than 30 minutes. Considering the Sun's intensity during midday, it's wise to minimize direct exposure. On sunny days, it's ideal to wear sunglasses that filter out UVA and UVB rays. Observe! Snow reflection can nearly intensify the Sun's UV radiation twofold.
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Frequently asked questions

What are the temperatures in Evanston in September?

September temperatures vary between a high-temperature of 68.5°F (20.3°C) and a low-temperature of 45°F (7.2°C).

What is the average humidity in September in Evanston?

In September, the average relative humidity in Evanston, Wyoming, is 44%.

How much does it rain in Evanston in September?

In September, in Evanston, Wyoming, the rain falls for 8 days. Throughout September, 0.71" (18mm) of precipitation is accumulated.

When does it start snowing in Evanston?

September is the first month it typically snows in Evanston, Wyoming. Throughout September, in the average 1.1 snowfall days, it receives 0.91" (23mm) of snow.

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

In September, the average day length in Evanston is 12h and 27min.

When is the sunrise / sunset in September in Evanston?

In September, on the first day of the month, sunrise is at 6:51 am and sunset at 7:56 pm. On the last day of the month, in Evanston, sunrise is at 7:20 am and sunset at 7:06 pm MDT.

How long on average sun shines in September in Evanston?

In September, the average sunshine duration in Evanston, Wyoming, is 10.3h.

How high is the UV index in September in Evanston?

In September, the average daily maximum UV index in Evanston, Wyoming, is 4. A UV Index value of 3 to 5 symbolizes 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
Evanston, WY

Average temperature in September - Evanston, WY
  • Average high temperature in September: 68.5°F

The warmest month (with the highest average high temperature) is July (79.2°F).
The month with the lowest average high temperature is December (26.4°F).

  • Average low temperature in September: 45°F

The month with the highest average low temperature is July (51.6°F).
The coldest month (with the lowest average low temperature) is January (10.8°F).

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Average pressure in September
Evanston, WY

Average pressure in September - Evanston, WY
  • Average pressure in September: 29.96"Hg

The month with the highest atmospheric pressure is January (30.29"Hg).
The month with the lowest atmospheric pressure is June (29.88"Hg).

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Average wind speed in September
Evanston, WY

Average wind speed in September - Evanston, WY
  • Average wind speed in September: 7.3mph

The windiest month (with the highest average wind speed) is April (8.2mph).
The calmest month (with the lowest average wind speed) is July (6.7mph).

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Average humidity in September
Evanston, WY

Average humidity in September - Evanston, WY
  • Average humidity in September: 44%

The months with the highest relative humidity are January and February (87%).
The month with the lowest relative humidity is August (39%).

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Average rainfall in September
Evanston, WY

Average rainfall in September - Evanston, WY
  • Average rainfall in September: 0.71"

The wettest months (with the highest rainfall) are April and May (1.38").
The driest month (with the least rainfall) is August (0.51").

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Average rainfall days in September
Evanston, WY

Average rainfall days in September - Evanston, WY
  • Average rainfall days in September: 8 days

The month with the highest number of rainy days is May (11.9 days).
The month with the least rainy days is February (5.5 days).

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Average snowfall in September
Evanston, WY

Average snowfall in September - Evanston, WY
  • Average snowfall in September: 0.91"

The month with the highest snowfall is March (10").
The months with the least snowfall are July and August (0").

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Average snowfall days in September
Evanston, WY

Average snowfall days in September - Evanston, WY
  • Average snowfall days in September: 1.1 days

The month with the highest number of snowfall days is February (16.3 days).
The months with the least snowfall days are July and August (0 days).

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Average daylight in September /
Average sunshine in September
Evanston, WY

Average daylight in September / Average sunshine in September - Evanston, WY
  • Average daylight in September: 12h and 3min

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

  • Average sunshine in September: 10h and 2min

The month with the most sunshine is August (Average sunshine: 12h and 0min).
The month with the least sunshine is January (Average sunshine: 5h and 48min).

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Average sunshine days in September
Evanston, WY

Average sunshine days in September - Evanston, WY
  • Average sunshine days in September: 17 days

The month with the most sunshine days is June (19.5 days).
The month with the least sunshine days is April (10.8 days).

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Average UV index in September
Evanston, WY

Average UV index in September - Evanston, WY
  • Average UV index in September: 4

The months with the highest UV index are June, July and August (UV index 5).
The months with the lowest UV index are November and December (UV index 1).

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Average cloud cover in September
Evanston, WY

Average cloud cover in September - Evanston, WY
  • Average cloud cover in September: 13

The month with the most cloud cover is February (Cloud cover 45).
The month with the least cloud cover is August (Cloud cover 10).

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Average visibility in September
Evanston, WY

Average visibility in September - Evanston, WY
  • Average visibility in September: 6mi

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

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Evanston, Wyoming, USA

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