Mattoon, Illinois climate: Normal weather by month, frost dates and records
Mattoon's normal year runs from 20°F January nights to 86°F July afternoons, with 36.0 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 11.9°C, January lows of −6°C, July highs of 30°C, 914 mm of precipitation a year.
- NOAA stationMattoon Coles County Airport
- Station IDUSW00053802
- Location39.48°N 88.28°W
- Elevation721 ft (220 m)
- From the center4 miles
- Population16,602
On October 23, the normal high in Mattoon is 63°F and the normal low 43°F, and the chance of measurable rain or snow is 28%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Mattoon.
- Jan 35° 20°
- Feb 40° 24°
- Mar 52° 33°
- Apr 64° 43°
- May 74° 54°
- Jun 83° 63°
- Jul 86° 66°
- Aug 84° 64°
- Sep 79° 56°
- Oct 66° 45°
- Nov 51° 35°
- Dec 40° 26°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Mattoon each month?
July is the warmest month, with normal highs of 86°F; January the coldest, with normal lows of 20°F. The most precipitation falls in June (4.72 in), the least in February (1.81 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 35°F | 20°F | 27.8°F | 2.04 | 8 | <1 | 26 | 9 h 40 min |
| February | 40°F | 24°F | 32.0°F | 1.81 | 8 | <1 | 22 | 10 h 40 min |
| March | 52°F | 33°F | 42.6°F | 2.22 | 9 | <1 | 16 | 11 h 50 min |
| April | 64°F | 43°F | 53.6°F | 4.14 | 10 | <1 | 4 | 13 h 10 min |
| May | 74°F | 54°F | 63.9°F | 3.86 | 12 | <1 | <1 | 14 h 20 min |
| June | 83°F | 63°F | 72.8°F | 4.72 | 10 | 4 | <1 | 15 h |
| July | 86°F | 66°F | 75.7°F | 3.96 | 10 | 7 | <1 | 14 h 40 min |
| August | 84°F | 64°F | 73.9°F | 2.42 | 9 | 5 | <1 | 13 h 50 min |
| September | 79°F | 56°F | 67.4°F | 2.85 | 8 | 3 | <1 | 12 h 30 min |
| October | 66°F | 45°F | 55.6°F | 3.11 | 8 | <1 | 3 | 11 h 10 min |
| November | 51°F | 35°F | 42.9°F | 3.03 | 8 | <1 | 13 | 10 h |
| December | 40°F | 26°F | 33.0°F | 1.84 | 8 | <1 | 23 | 9 h 20 min |
| Year (annual) | 63°F | 44°F | 53.4°F | 36.00 | 108 | 20 | 106 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 2°C | −6°C | −2.3°C | 52 mm |
| February | 5°C | −5°C | 0.0°C | 46 mm |
| March | 11°C | 1°C | 5.9°C | 56 mm |
| April | 18°C | 6°C | 12.0°C | 105 mm |
| May | 23°C | 12°C | 17.7°C | 98 mm |
| June | 28°C | 17°C | 22.7°C | 120 mm |
| July | 30°C | 19°C | 24.3°C | 101 mm |
| August | 29°C | 18°C | 23.3°C | 61 mm |
| September | 26°C | 13°C | 19.7°C | 72 mm |
| October | 19°C | 7°C | 13.1°C | 79 mm |
| November | 11°C | 1°C | 6.1°C | 77 mm |
| December | 4°C | −3°C | 0.6°C | 47 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. Mattoon's own co-op station Mattoon station does: 15 inches of snow in a normal year (see the other stations below).
Source: NOAA NCEI 1991-2020 monthly normals, station USW00053802; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit Mattoon?
Normal highs sit between 65°F and 85°F in May, June, August, September and October. Of those, September has the fewest days with rain (8).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USW00053802.
When is the last frost in Mattoon?
In Mattoon, the last spring frost (32°F) comes after April 15 in half of years and after April 30 in one year in ten; the first autumn frost comes before October 24 in half of years and before October 9 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- April 151 year in 10 after April 30; 9 in 10 after April 2
- First autumn frost, half of years before
- October 241 year in 10 before October 9; 9 in 10 before November 5
NOAA puts the median frost-free season at 189 days, and the season without a hard freeze (28°F) at 214 days.
A hard freeze (28°F) comes after April 2 in half of springs and before November 3 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Mattoon in zone 6a in ZIP code 61938, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, Mattoon's NOAA station is in zone 6b: the coldest night of a typical year reaches −4°F (22 complete years); the map interpolates between stations and terrain, so the station and the ZIP area can differ by half a zone.
Frost dates for every NOAA station in Illinois · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USW00053802; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
How hot and how cold does it get in Mattoon?
In a normal year in Mattoon, 20 days a year reach 90°F (1 of them 100°F or more), 106 nights fall to 32°F or colder and 108 days bring measurable precipitation.
- Days at 90°F or more
- 20a normal year
- Days at 100°F or more
- 1a normal year
- Nights at 32°F or colder
- 106a normal year
- Days that stay below freezing
- 30high of 32°F or less
- Days with 0.01 inch of precipitation
- 108a normal year
The highest temperature in this station's record (since 1998) is 106°F, on July 7, 2012; the lowest is −14°F, on January 6, 2014.
The wettest calendar year on that record is 2021, with 49.20 in.
Source: NOAA NCEI 1991-2020 annual normals, station USW00053802; records: ACIS (NOAA Regional Climate Centers), station USW00053802. Records use complete months only; a month missing more than three days is left out.
How sunny is Mattoon?
Over a year 74% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Mattoon, 4.1 kWh per square metre a day. July is the sunniest month (83%) and December the cloudiest (61%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 62% | 1.9 |
| February | 65% | 2.7 |
| March | 67% | 3.7 |
| April | 72% | 4.9 |
| May | 73% | 5.5 |
| June | 81% | 6.4 |
| July | 83% | 6.3 |
| August | 82% | 5.6 |
| September | 81% | 4.7 |
| October | 74% | 3.3 |
| November | 70% | 2.3 |
| December | 61% | 1.6 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does Mattoon need?
A normal year in Mattoon brings 5,297 heating degree days, 1% fewer than the median U.S. place (5,373), and 1,116 cooling degree days, 23% more than the median (908). Seven months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 3,698 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,151 | 0 |
| February | 924 | 0 |
| March | 697 | 3 |
| April | 354 | 12 |
| May | 124 | 91 |
| June | 12 | 244 |
| July | 1 | 331 |
| August | 3 | 277 |
| September | 61 | 133 |
| October | 316 | 25 |
| November | 662 | 1 |
| December | 992 | 0 |
| Year (annual) | 5,297 | 1,116 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00053802. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Has Mattoon been warmer than normal lately?
2025 averaged 54.2°F, 0.8°F above the 1991-2020 normal of 53.4°F. 3 of the 4 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 54.8°F | +1.4°F | 49.20 |
| 2022 | 53.4°F | at normal | 33.93 |
| 2023 | 55.5°F | +2.1°F | 28.56 |
| 2025 | 54.2°F | +0.8°F | 29.62 |
Source: observed years: ACIS, station USW00053802. A year counts only with all twelve months complete.
How does Mattoon's climate compare?
Mattoon is warmer than 99 of the other 143 places with their own NOAA record in Illinois, and wetter than 3. Across the 7,247 U.S. stations with normals, its annual mean of 53.4°F is warmer than 55%.
In the Köppen classification computed from these normals, Mattoon is Dfa: continental, no dry season, hot summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near Mattoon share this climate record?
5 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Toledo, IL1,141 people · 14 mi S
- Humboldt, IL356 people · 9 mi N
- Lerna, IL218 people · 4 mi S
- Trilla, IL118 people · 8 mi SW
- Janesville, IL14 people · 7 mi S
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
What do Mattoon's other NOAA stations record?
One more NOAA station keeps 1991-2020 normals in or near Mattoon. This page uses Mattoon Coles County Airport; the other differs by site and elevation:
| Station | From the center | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| Mattoon station USC00115430 | 1 mi SE | 701 ft | 53.6°F | 20°F | 86°F | 41.3 | 15 | April 11 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about Mattoon's climate
What is the coldest month in Mattoon?
January, with a normal high of 35°F and a normal low of 20°F. The warmest is July (86°F by day, 66°F at night).
Does it snow in Mattoon?
Yes. NOAA publishes no 1991-2020 snowfall normal for Mattoon's NOAA station; Mattoon's own co-op station Mattoon station records 15 inches of snow in a normal year.
What is the rainiest month in Mattoon?
June, with 4.72 in of precipitation in a normal year; the driest is February with 1.81 in.
What plant hardiness zone is Mattoon in?
The USDA's 2023 map puts Mattoon in zone 6a in ZIP code 61938, the nearest ZIP area. By the same method at Mattoon's NOAA station, the coldest night of a typical year reaches −4°F (22 years, 1991-2020): zone 6b.
How late can frost come in Mattoon?
In half of years the last 32°F night comes after April 15; in one year in ten it comes after April 30. Waiting until April 30 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Illinois climateThe statewide normals and every place in the state
- Charleston, IL6 miles from this station, 55.0°F a year
- Neoga, IL14 miles from this station, 53.6°F a year
- Windsor, IL17 miles from this station, 52.6°F a year
- Sullivan, IL19 miles from this station, 53.0°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made