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Chillicothe, IL Weather
Chillicothe, Illinois sits at 40.9160, -89.5027. Its warmest month is July, when the day usually reaches 86F, and its coldest is January, when the night usually falls to 17F. April is the wettest, with rain on about 12 days. The hottest day in the station record is 105F on June 25, 1988, and the coldest night -25F on January 17, 1977. This page carries live conditions, an hour by hour timeline, a ten day outlook, radar, monthly averages and searchable daily history back to 1940.
About Chillicothe weather
Chillicothe sits at 40.9160, -89.5027 and covers about 5.274 square miles. The forecast above is live: current conditions lead with the HRRR model, corrected against the nearest reporting station and against radar overhead, because a model can lag a storm and the radar cannot.
The tabs at the top of this page carry the hour by hour timeline, the ten day outlook and live radar. Where the models disagree about a day, the rock says so on the day rather than quietly picking a winner.
The rock grades itself against what actually happened and publishes the result whether it flatters it or not. Those standings live in the Receipts.
Where these numbers come from
Current conditions and forecast: NOAA forecast grids (the National Weather Service digital forecast, the National Blend of Models, HRRR and GFS) decoded on our own server, corrected against the nearest reporting station and our own radar. Open-Meteo is consulted only as a fallback when our server is silent.
Radar: NOAA MRMS merged reflectivity, rendered into tiles by myweatherrock.
Monthly averages and records: computed by myweatherrock from NOAA GHCN-Daily station records at the nearest qualifying station, named on this page with its distance. Measurements, not estimates.
Daily history search: the town's own NOAA GHCN-Daily station file, held on our server, measurements by day. Months the station missed fall back to the Open-Meteo historical archive (reanalysis), and the page says so when it does.
What the weather is usually like in Chillicothe
Chillicothe is warmest in July, when the day usually reaches 86F, and coldest in January, when the night usually falls to 17F. April is the wettest month, with rain on about 12 days of it.
Usual high and low, by month
Days with rain, by month
The same year as numbers
Month
Usual high
Usual low
Rain days
Snow days
January
33F
17F
10
6
February
38F
21F
9
5
March
51F
31F
10
2
April
63F
42F
12
1
May
74F
53F
12
0
June
83F
62F
11
0
July
86F
66F
9
0
August
84F
64F
8
0
September
78F
56F
8
0
October
65F
44F
9
0
November
50F
33F
9
1
December
38F
23F
10
4
Thirty-year normals, 1991 to 2020, computed from the daily record, measured at the General Wayne A Downing Intl A station 19.6 miles away. A rain day means at least a hundredth of an inch fell, the same measurable-precipitation mark the Weather Service uses. Source: computed from the station record, NOAA GHCN daily.
Chillicothe weather history, back to 1940
Pick any month back to 1940 and see what the archive holds for Chillicothe: the reanalysis record of what happened, day by day.
Reading this month last year to start you off.
Chillicothe weather records
In 119,147 days of observations Chillicothe has been as hot as 105F and as cold as -25F. Not averages: the actual days.
Hottest day
105F
June 25, 1988
Coldest night
-25F
January 17, 1977
Wettest day
5.47 in
July 16, 1977
Biggest snow
13.0 in
December 1, 2006
NOAA GHCN daily station records, observed 1943 to 2025: temperature at the General Wayne A Downing Intl A station, 19.6 miles away; precipitation at the Lacon station, 8.4 miles away. Station measurements, not estimates. Record dates reflect the station's own observation schedule, and the official state record may live at a different station.
Common questions about Chillicothe weather
Common questions
What is the weather usually like in Chillicothe, IL?
Chillicothe is warmest in July, when the day usually reaches 86F, and coldest in January, when the night usually falls to 17F. Rain falls on roughly 117 days a year, most often in April. Averages are thirty-year normals, 1991 to 2020, computed from the nearest NOAA station's own daily record.
How much does it rain in Chillicothe, IL?
About 117 days a year see at least a hundredth of an inch, which is the Weather Service's measurable-precipitation mark. April is the wettest month with rain on about 12 of its days, and August the driest with about 8.
Does it snow in Chillicothe, IL?
Yes. Snow falls on about 19 days a year, most often in January, which averages about 6 snowy days. Those are days with measurable snowfall, not days with snow lying on the ground.
What is the hottest it has ever been in Chillicothe, IL?
The hottest day measured for Chillicothe reached 105F on June 25, 1988, and the coldest night -25F on January 17, 1977. Both are real NOAA station measurements from the GHCN daily archive, observed 1943 to 2025, at the General Wayne A Downing Intl A station. Not estimates, though the official state record may live at a different station.
Can I look up past weather for Chillicothe, IL?
Yes, and for free. The History tab on this page takes any month back to 1940 and shows every day of it: the high, the low, what fell, and that month's hottest and coldest day. No account and no payment.
Is the Chillicothe forecast on this page free, and does it track me?
It is free, carries no advertising, and needs no account. Nothing about a visitor leaves the device except the coordinates needed to fetch a forecast, and those are not stored against anyone.