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.
Decatur Travel Guide
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)
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Decatur Temperatures (Celsius)
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“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)
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Decatur Perceived Temperature (C)
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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) |
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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) |
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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.
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Snow on the Ground
The graph below shows the average snow on the ground in Decatur (in).
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Average Rain and Snow by Month
Show Inches
Month | Daily Chance of Rain | Average Snow Depth (in) | Total Precipitation (in) |
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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.
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Wind
The graph below shows wind speed (max and average) in knots.
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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 |
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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
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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