September weather forecast
Westmont, IL

Share

Weather in September

September, the first month of the autumn in Westmont, is still a warm month, with an average temperature varying between 57.9°F (14.4°C) and 74.3°F (23.5°C).

Temperature

September signifies a minor drop in average high-temperature, transitioning from a moderately hot 81.1°F (27.3°C) in August to a still warm 74.3°F (23.5°C). Westmont records an average low of 57.9°F (14.4°C) throughout the nights in September.

Humidity

In September, the average relative humidity is 75%.

Rainfall

In Westmont, in September, it is raining for 11.5 days, with typically 1.18" (30mm) of accumulated precipitation. In Westmont, during the entire year, the rain falls for 118.5 days and collects up to 13.74" (349mm) of precipitation.

Snowfall

In Westmont, snow does not fall in May through September.

Daylight

The average length of the day in September in Westmont, Illinois, is 12h and 28min.
On the first day of the month, sunrise is at 6:18 am and sunset at 7:24 pm. On the last day of September, sunrise is at 6:48 am and sunset at 6:34 pm CDT.

Sunshine

The average sunshine in September is 8.7h.

UV index

The average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a medium vulnerability from unsafe exposure to UV radiation for ordinary individuals.
Note: The daily maximum UV index of 4 in September interprets into the following advice:
Take care. Persons with lighter skin might suffer burns in less than 30 minutes. To avoid the Sun's strongest rays, limit exposure around the mid-day period. To mitigate harm from sun exposure, pick sunglasses offering UVA and UVB defense.
Updated: Aug 17, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the usual temperature for Westmont in September?

In Westmont, in September, the average high-temperature is 74.3°F (23.5°C), and the average low-temperature is 57.9°F (14.4°C). In August, the average heat index (a.k.a. 'felt air temperature', 'real feel'), which factors the actual air temperature with the relative humidity, is computed to be 86°F (30°C).

What is the average humidity in September?

In September, the average relative humidity is 75%.

How many days does it rain in September?

In Westmont, Illinois, during September, the rain falls for 11.5 days and regularly aggregates up to 1.18" (30mm) of precipitation.

When it does not snow?

In Westmont, Illinois, snow does not fall in May through September.

Does it snow in September?

In Westmont, in September, it doesn't snow. In October, it regularly snows.

How many hours of daylight does Westmont have in September?

In Westmont, the average day length in September is 12h and 28min.

When are sunrise and sunset in September?

In September, on the first day of the month, sunrise is at 6:18 am and sunset at 7:24 pm. On the last day of the month, sunrise is at 6:48 am and sunset at 6:34 pm CDT.

How many hours of sunshine does Westmont have in September?

In Westmont, the average sunshine duration in September is 8.7h.

What is the UV index reading in September?

The average daily maximum UV index in September is 4. A UV Index reading of 3 to 5 represents a moderate health threat from unprotected exposure to UV radiation.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Westmont, IL

Average temperature in September - Westmont, IL
  • Average high temperature in September: 74.3°F

The warmest month (with the highest average high temperature) is July (82.4°F).
The month with the lowest average high temperature is January (28.8°F).

  • Average low temperature in September: 57.9°F

The month with the highest average low temperature is July (66.4°F).
The coldest month (with the lowest average low temperature) is January (17.1°F).

Average pressure in September
Westmont, IL

Average pressure in September - Westmont, IL
  • Average pressure in September: 30.03"Hg

The month with the highest atmospheric pressure is January (30.11"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).

Average wind speed in September
Westmont, IL

Average wind speed in September - Westmont, IL
  • Average wind speed in September: 7mph

The windiest month (with the highest average wind speed) is January (9.7mph).
The calmest month (with the lowest average wind speed) is August (6.1mph).

Average humidity in September
Westmont, IL

Average humidity in September - Westmont, IL
  • Average humidity in September: 75%

The months with the highest relative humidity are January and February (82%).
The month with the lowest relative humidity is October (72%).

Average rainfall in September
Westmont, IL

Average rainfall in September - Westmont, IL
  • Average rainfall in September: 1.18"

The wettest month (with the highest rainfall) is May (1.97").
The driest month (with the least rainfall) is December (0.63").

Average rainfall days in September
Westmont, IL

Average rainfall days in September - Westmont, IL
  • Average rainfall days in September: 11.5 days

The month with the highest number of rainy days is May (14.9 days).
The month with the least rainy days is February (4.2 days).

Average snowfall in September
Westmont, IL

Average snowfall in September - Westmont, IL
  • Average snowfall in September: 0"

The month with the highest snowfall is February (2.28").
The months with the least snowfall are May, June, July, August and September (0").

Average snowfall days in September
Westmont, IL

Average snowfall days in September - Westmont, IL
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (9.7 days).
The months with the least snowfall days are June, July, August and September (0 days).

Average daylight in September /
Average sunshine in September
Westmont, IL

Average daylight in September / Average sunshine in September - Westmont, IL
  • Average daylight in September: 12h and 3min

The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 12min).

  • Average sunshine in September: 8h and 4min

The month with the most sunshine is August (Average sunshine: 10h and 0min).
The month with the least sunshine is January (Average sunshine: 3h and 42min).

Average sunshine days in September
Westmont, IL

Average sunshine days in September - Westmont, IL
  • Average sunshine days in September: 16.1 days

The month with the most sunshine days is December (20.7 days).
The month with the least sunshine days is July (11.8 days).

Average UV index in September
Westmont, IL

Average UV index in September - Westmont, IL
  • Average UV index in September: 4

The months with the highest UV index are June, July and August (UV index 6).
The month with the lowest UV index is January (UV index 1).

Average cloud cover in September
Westmont, IL

Average cloud cover in September - Westmont, IL
  • Average cloud cover in September: 32

The month with the most cloud cover is January (Cloud cover 61).
The month with the least cloud cover is August (Cloud cover 31).

Average visibility in September
Westmont, IL

Average visibility in September - Westmont, IL
  • Average visibility in September: 6mi

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

Westmont, Illinois, USA

Weather forecast for your location

1. Click Locate me button
2. Allow the app to use your location