The best times to visit Decatur for ideal weather are

April 23rd to June 17th

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

 

 


Other Decatur Travel Info

Weather in Decatur

Temperature

Average temperatures in Decatur vary drastically. Considering humidity, temperatures feel cold for about half of the year and otherwise nice with a fair chance of precipitation about half of the year. The area is less temperate than some — in the 26th 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 Decatur, 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 87.5°F (30.8°C) with temperatures rarely dropping below 66.7°F (19.3°C) at night.

Decatur Temperatures (Fahrenheit)

Key
High
Average
Low

Decatur Temperatures (Celsius)

Key
High
Average
Low

“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.

Decatur Perceived Temperature (F)

Key
High
Average
Low

Decatur Perceived Temperature (C)

Key
High
Average
Low

 

Average Decatur 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 36.1 26.7 18.6
Feb 37.5 28 20
Mar 55.1 43.1 33.6
Apr 66.5 54.2 43.2
May 76.9 65.3 54.3
Jun 85 74 63.4
Jul 86.6 75.9 65.4
Aug 86.4 74.8 63.5
Sep 80.5 67.4 55.8
Oct 67.9 55.7 45.1
Nov 53.9 43.4 34.1
Dec 41.1 33.1 26.2

Show Celsius

Month Avg. High (°C) Avg. Mean (°C) Avg. Low (°C)
Jan 2.3 -2.9 -7.4
Feb 3.1 -2.2 -6.7
Mar 12.8 6.2 0.9
Apr 19.2 12.3 6.2
May 24.9 18.5 12.4
Jun 29.4 23.3 17.4
Jul 30.3 24.4 18.6
Aug 30.2 23.8 17.5
Sep 26.9 19.7 13.2
Oct 19.9 13.2 7.3
Nov 12.2 6.3 1.2
Dec 5.1 0.6 -3.2

 


 

Precipitation (Rain or Snow)

If dry weather is what you’re after, the months with the lowest chance of significant precipitation in Decatur are January, August, and then February. Note that we define “significant precipitation” as .1 inches or more in this section. The lowest chance of rain or snow occurs around early January. For example, on the week of January 1st there is 1 day of precipitation on average. By contrast, it’s most likely to rain or snow in mid June with an average of 3 days of significant precipitation the week of June 18th.

When can you find snow in Decatur? 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 Decatur.

Key
Days with precipitation

Snow on the Ground

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

Key
Snow depth

Average Rain and Snow by Month

Show Inches

Month Daily Chance of Rain Average Snow Depth (in) Total Precipitation (in)
Jan 11% 0 1.4
Feb 16% 0 2.2
Mar 17% 0 1.9
Apr 26% 0 4.1
May 29% 0 4.2
Jun 29% 0 6
Jul 18% 0 3.4
Aug 14% 0 2.1
Sep 20% 0 3.9
Oct 18% 0 3.5
Nov 19% 0 2.9
Dec 21% 0 3.4

Show Centimeters

Month Daily Chance of Rain Average Snow Depth (cm) Total Precipitation (cm)
Jan 11 0 3.6
Feb 16 0 5.6
Mar 17 0 4.8
Apr 26 0 10.4
May 29 0 10.7
Jun 29 0 15.2
Jul 18 0 8.6
Aug 14 0 5.3
Sep 20 0 9.9
Oct 18 0 8.9
Nov 19 0 7.4
Dec 21 0 8.6

 

Humidity and Wind

Decatur has some very humid months, with other comfortably humid months. The least humid month is April (54.1% relative humidity), and the most humid month is December (71.8%).

Wind in Decatur is usually moderate. The windiest month is April, followed by January and February. April’s average wind speed of around 10 knots (11.5 MPH or 18.5 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 17.9 knots, which is considered a fresh breeze.

Relative Humidity (%)

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

Key
Avg. Relative Humidity

Wind

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

Key
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 9.8 Gentle breeze 16.3 Significant breeze
Feb 9.7 Gentle breeze 16.5 Significant breeze
Mar 9.7 Gentle breeze 16.5 Significant breeze
Apr 10 Gentle breeze 17.2 Strong breeze
May 8.3 Gentle breeze 15.3 Significant breeze
Jun 7.1 Gentle breeze 14.8 Significant breeze
Jul 5.7 Light breeze 12 Significant breeze
Aug 5.5 Light breeze 11.5 Significant breeze
Sep 6.1 Light breeze 12.3 Significant breeze
Oct 8 Gentle breeze 14.1 Significant breeze
Nov 9.1 Gentle breeze 15.4 Significant breeze
Dec 9.3 Gentle breeze 15.5 Significant breeze

Show Relative Humidity by Month

Month Avg. Relative Humidity
Jan 64.3%
Feb 62.9%
Mar 59.3%
Apr 54.1%
May 57.8%
Jun 61.3%
Jul 62.8%
Aug 61.6%
Sep 59.6%
Oct 56.8%
Nov 60.7%
Dec 71.8%

 

Is it Safe to Travel to Decatur?

Our best data indicates this area is generally safe. As of Dec 04, 2023 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 Dec 04, 2023.


 

The Busiest and Least Crowded Months

The busiest month for tourism in Decatur, IL, US 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 Decatur 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

Key
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 Decatur Travel Experience by Season

Spring (March through May)

Humidity and temperatures combine to make this season feel moderately cold. Highs range from 81.8°F (27.7°C) and 41.3°F (5.2°C) with far warmer temperatures in the later months. Rain is somewhat common with 5 to 9 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 moderate precipitation with 4 to 9 days of precipitation per month. June – August is the busiest season for tourism in Decatur, so lodging and other accommodations may cost more than usual.

Fall (September through November)

Fall daily highs range from 83°F (28.3°C) and 46.7°F (8.2°C), which will feel chilly given the humidity and wind. It rains or snows a significant amount: approximately 6 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 Decatur to be enjoyable for warm weather travelers. The average high during this season is between 41.3°F (5.2°C) and 34.9°F (1.6°C). On average, it rains or snows a fair amount: 3 to 6 times per month. These times of year are fairly slow with tourists.

 

Best Times to Travel› the United States › Decatur, IL, US