The best times to visit Western Illinois for ideal weather are

April 30th to October 14th

based on average temperature and humidity from NOAA (the National Oceanic and Atmospheric Administration). Read below for more weather and travel details.



Other Western Illinois Travel Info

Weather in Western Illinois


Average temperatures in Western Illinois vary drastically. Considering humidity, temperatures feel cold for about half of the year and otherwise nice with a very low chance of rain or snow throughout the year. The area is somewhat temperate — in the 48th percentile for pleasant weather — compared to tourist destinations worldwide. Weeks with ideal weather are listed above. If you’re looking for the very warmest time to visit Western Illinois, the hottest months are July, August, and then June. See average monthly temperatures below. The warmest time of year is generally mid July where highs are regularly around 86.2°F (30.1°C) with temperatures rarely dropping below 65.7°F (18.7°C) at night.

Western Illinois Temperatures (Fahrenheit)


Western Illinois Temperatures (Celsius)


“Feels-Like” Temperatures

The way we experience weather isn’t all about temperature. Higher temperatures affect us much more at higher humidity, and colder temperatures feel piercing with high winds. Our perceived temperatures factor in humidity and wind chill to better represent how hot or cold the day feels to a person.

Western Illinois Perceived Temperature (F)


Western Illinois Perceived Temperature (C)



Average Western Illinois Temperatures by Month

Daily highs (averaged for the month) usually give the best indication of the weather. A significantly lower mean and low generally just means it gets colder at night.

Show Fahrenheit

Month Avg. High (°F) Avg. Mean (°F) Avg. Low (°F)
Jan 34.4 24.6 16.5
Feb 35.2 25.5 17.5
Mar 53.3 41.4 32.8
Apr 66.4 53.2 42.2
May 77.2 64.8 53.8
Jun 83.8 72.8 62.8
Jul 85.4 74.7 64.6
Aug 84.9 73.1 62.6
Sep 79.8 66 54.4
Oct 67.8 54.5 43.6
Nov 53.6 42.1 32.8
Dec 38.7 30.4 23.2

Show Celsius

Month Avg. High (°C) Avg. Mean (°C) Avg. Low (°C)
Jan 1.3 -4.1 -8.6
Feb 1.8 -3.6 -8.1
Mar 11.8 5.2 0.4
Apr 19.1 11.8 5.7
May 25.1 18.2 12.1
Jun 28.8 22.7 17.1
Jul 29.7 23.7 18.1
Aug 29.4 22.8 17
Sep 26.6 18.9 12.4
Oct 19.9 12.5 6.4
Nov 12 5.6 0.4
Dec 3.7 -0.9 -4.9



Precipitation (Rain or Snow)

If dry weather is what you’re after, the months with the lowest chance of significant precipitation in Western Illinois are August, March, and then July. Note that we define “significant precipitation” as .1 inches or more in this section. The lowest chance of rain or snow occurs around late February and early March. For example, on the week of February 26th there are no days of precipitation on average. By contrast, it’s most likely to rain or snow in late October with an average of 1 days of significant precipitation the week of October 22nd.

When can you find snow in Western Illinois? Weather stations report no annual snow. Please note that a value of 0 for snow in the graph below may either mean there was no snow, or that snow is unreported.

Chance of Precipitation

The graph below shows the % chance of rainy and snowy days in Western Illinois.

Days with precipitation

Snow on the Ground

The graph below shows the average snow on the ground in Western Illinois (in).

Snow depth

Average Rain and Snow by Month

Show Inches

Month Daily Chance of Rain Average Snow Depth (in) Total Precipitation (in)
Jan 6% 0 0.8
Feb 5% 0 0.6
Mar 3% 0 0.4
Apr 9% 0 1.5
May 7% 0 1.2
Jun 10% 0 2.4
Jul 4% 0 0.9
Aug 3% 0 0.9
Sep 6% 0 1.2
Oct 11% 0 2.1
Nov 7% 0 1.4
Dec 10% 0 1.4

Show Centimeters

Month Daily Chance of Rain Average Snow Depth (cm) Total Precipitation (cm)
Jan 6 0 2
Feb 5 0 1.5
Mar 3 0 1
Apr 9 0 3.8
May 7 0 3
Jun 10 0 6.1
Jul 4 0 2.3
Aug 3 0 2.3
Sep 6 0 3
Oct 11 0 5.3
Nov 7 0 3.6
Dec 10 0 3.6


Humidity and Wind

Western Illinois has some very humid months, with other comfortably humid months. The least humid month is April (54.2% relative humidity), and the most humid month is December (77.4%).

Wind in Western Illinois is usually moderate. The windiest month is April, followed by January and February. April’s average wind speed of around 9.8 knots (11.3 MPH or 18.2 KPH) is considered “a gentle breeze.” Maximum sustained winds (the highest speed for the day lasting more than a few moments) are at their highest in early April where average top sustained speeds reach 18.8 knots, which is considered a fresh breeze.

Relative Humidity (%)

The graph below shows the average % humidity by month in Western Illinois.

Avg. Relative Humidity


The graph below shows wind speed (max and average) in knots.

Max Sustained Wind
Average Daily Wind

Average Wind Speeds

Show Wind Speeds

All wind speeds are in knots. 1 knot = 1.15 MPH or 1.85 KPH.

Month Avg. Wind Avg. Wind Feel Sustained High Wind High Wind Feel
Jan 9.4 Gentle breeze 17.1 Strong breeze
Feb 9.4 Gentle breeze 17.1 Strong breeze
Mar 9 Gentle breeze 16.6 Strong breeze
Apr 9.8 Gentle breeze 18.5 Strong breeze
May 8.3 Gentle breeze 16.5 Strong breeze
Jun 6.6 Light breeze 15.2 Significant breeze
Jul 4.5 Light breeze 10.8 Strong breeze
Aug 4 Light breeze 10.3 Gentle breeze
Sep 5 Light breeze 11.7 Strong breeze
Oct 7.2 Gentle breeze 14.5 Significant breeze
Nov 8.8 Gentle breeze 16.1 Strong breeze
Dec 8.5 Gentle breeze 15.5 Significant breeze

Show Relative Humidity by Month

Month Avg. Relative Humidity
Jan 69.8%
Feb 70.2%
Mar 64.5%
Apr 54.2%
May 55.7%
Jun 65.3%
Jul 68.3%
Aug 69.5%
Sep 63.8%
Oct 58.7%
Nov 62.8%
Dec 77.4%


Is it Safe to Travel to Western Illinois?

Our best data indicates this area is generally safe. As of Oct 07, 2019 there are no travel advisories or warnings for the United States; exercise normal security precautions. Check this page for any recent changes or regions to avoid: Travel Advice and Advisories. This advisory was last updated on Sep 23, 2019.


The Busiest and Least Crowded Months

The busiest month for tourism in Western Illinois, the United States is July, followed by June and August. Prices for hotels and flights will be most expensive during these months, though you can save if you purchase well in advance. Tourists are unlikely to visit Western Illinois in November. Those willing to visit at these times will likely find it the least expensive month.

Estimated Tourism by Month


Most Popular Months to Visit

Tourists Seeking Accommodations

Tourism graph is based on Google searches for services used by tourists relative to the rest of the year. Tourism data for this area is extrapolated based on nearby areas. Displayed data is calculated relative to the peak, so a score of 38.7 in November means 38.7% of the tourists vs. July.



Overall Western Illinois Travel Experience by Season

Spring (March through May)

Humidity and temperatures combine to make this season feel moderately cold. Highs range from 81.4°F (27.4°C) and 38.1°F (3.4°C) with far warmer temperatures in the later months. Rain is rare with 1 to 3 days of significant precipitation per month. Spring is the second busiest for tourism, which makes it a good time for those looking for things to do.

Summer (June through August)

The middle-year months have very comfortable weather with high temperatures that are quite warm. These months see the least precipitation with 1 to 3 days of precipitation per month. June – August is the busiest season for tourism in Western Illinois, so lodging and other accommodations may cost more than usual.

Fall (September through November)

Fall daily highs range from 82.5°F (28.1°C) and 45°F (7.2°C), which will feel chilly given the humidity and wind. It rains or snows a normal amount: 2 to 3 days per month. Tourism is the slowest during these months due to the weather, so hotels may be affordably priced.

Winter (December through February)

Weather is far too cold this time of year in Western Illinois to be enjoyable for warm weather travelers. The average high during this season is between 39.1°F (3.9°C) and 33.4°F (0.8°C). On average, it rains or snows a smalll amount: 1 to 3 times per month. These times of year are fairly slow with tourists.


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