Mattoon climate — normals and trends
Mattoon (United States) has a hot-summer humid continental climate (Dfa) under the Köppen-Geiger classification. Its mean annual temperature is 11.9 °C and it receives 993 mm of precipitation per year.
These figures are normals computed over 86 complete calendar years, from 1940 to 2025, using ERA5 reanalysis data from the Copernicus programme.
The warmest month is July (24.5 °C on average) and the coldest is January (-2.4 °C). Rainfall peaks in April.
Mattoon averages 100 frost days, 40 hot days (≥ 30 °C) and 113 rainy days per year.
Mattoon has warmed by +1.7 °C between 1940 and 2025, or +0.20 °C per decade. This trend is statistically significant.
The number of frost days there went from about 111 to 89 per year over the period.
The hottest day of the period reached 39.9 °C (on 14 July 1954) and the coldest -31.3 °C (on 17 January 1982).
Data from ERA5 reanalysis (Copernicus Climate Change Service), redistributed under a CC-BY 4.0 licence. Normals are recomputed whenever the archive is updated.
Climate normals · ERA5
MattoonIllinois
- coords
- 39.48°, -88.37°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
11.9°C
Average daily high
16.8°C
Average daily low
7.2°C
Annual rainfall
993mm
Sunshine / day
8.9h
Mean relative humidity
69%
Average peak wind
19.4km/h
Seasonal range
26.9°C
Frost days (< 0 °C)
100 d/yr
Hot days (≥ 30 °C)
40 d/yr
Rainy days (≥ 1 mm)
113 d/yr
Annual snowfall
45.0 cm
Average feels-like high
15.2 °C
Average feels-like low
4.6 °C
Average peak gust
38.6 km/h
Tropical nights (≥ 20 °C)
45 d/yr
Solar radiation
15.4 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.7 °C
since 1940
+0.2 °C per decade · r² = 0.32 · p = < 0.001
Trend fitted by linear regression (ordinary least squares) on annual means. A trend is shown only when it is statistically significant (p < 0.05).
A climograph overlays rainfall (bars) and temperature (line): the standard reading in climatology, where you can see at a glance whether the warm season is also the dry one.
Records for the period
Hottest day
39.9 °C
14 July 1954
Coldest day
-31.3 °C
17 January 1982
Wettest day
101 mm
8 September 2018
Windiest day
57.7 km/h
5 April 1947
Strongest gust
108.4 km/h
10 November 1998
Hottest feels-like
44.8 °C
16 August 1988
Coldest feels-like
-38.5 °C
20 January 1985
Snowiest day
29.2 cm
19 December 1973
Sunniest day
14.1 h
11 June 2025
Normals computed over complete calendar years 1940–2025.
A specific year
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Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | -0.2 °C | -1.9 °C | 42 mm | -24 mm |
| Feb | 4.5 °C | +0.2 °C | 34 mm | -30 mm |
| Mar | 15.5 °C | +5.1 °C | 86 mm | -10 mm |
| Apr | 19.0 °C | +1.7 °C | 153 mm | +44 mm |
| May | 22.2 °C | -0.6 °C | 102 mm | -4 mm |
| Jun | 28.5 °C | +0.8 °C | 167 mm | +73 mm |
| Jul | 30.1 °C | +0.9 °C | 153 mm | +66 mm |
| Aug | 28.2 °C | -0.3 °C | 19 mm | -53 mm |
| Sep | 27.7 °C | +2.3 °C | 51 mm | -18 mm |
| Oct | 20.9 °C | +2.0 °C | 60 mm | -18 mm |
| Nov | 11.9 °C | +1.2 °C | 70 mm | -14 mm |
| Dec | 4.3 °C | +0.1 °C | 42 mm | -29 mm |
The year's extremes
What was the weather like that day?
Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.
Frequently asked questions
What is the climate of Mattoon?
Mattoon has a hot-summer humid continental climate (Köppen Dfa). Over 1940-2025, the average annual temperature is 11.9 °C and it receives 993 mm of precipitation per year.
What is the hottest day ever recorded in Mattoon?
The hottest day measured in Mattoon between 1940 and 2025 was 14 July 1954, reaching 39.9 °C.
What is the coldest day in Mattoon?
The coldest day measured in Mattoon between 1940 and 2025 was 17 January 1982, at -31.3 °C.
Does it snow in Mattoon?
Yes. Mattoon gets on average 45.0 cm of snow per year and has around 100 frost days.
Has the climate of Mattoon warmed?
Yes: Mattoon warmed by +1.7 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Mattoon?
The wettest day measured in Mattoon between 1940 and 2025 was 8 September 2018, with 101 mm of rain in 24 hours.
What was the windiest day in Mattoon?
The windiest day measured in Mattoon between 1940 and 2025 was 5 April 1947, with winds reaching 57.7 km/h.
What is the warmest month in Mattoon?
The warmest month in Mattoon is July (24.5 °C on average); the coldest is January (-2.4 °C).
How much does it rain in Mattoon?
Mattoon receives on average 993 mm of precipitation per year, spread over about 113 rainy days.
Is it sunny in Mattoon?
Mattoon gets on average 8.9 hours of sunshine per day, roughly 3,249 hours per year over 1940-2025.
What is the biggest single-day snowfall in Mattoon?
The heaviest 24-hour snowfall measured in Mattoon between 1940 and 2025 was 19 December 1973, with 29.2 cm.
Are there tropical nights in Mattoon?
Yes: Mattoon has on average 45 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Mattoon?
In Mattoon, between 1940 and 2025, the highest apparent temperature reached 44.8 °C on 16 August 1988, and the lowest was -38.5 °C on 20 January 1985.
Compare Mattoon with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Mattoon