Weather & Climate in Decatur, IL

Temperature, precipitation, air quality, natural hazards, and monthly weather data.

Decatur experiences four distinct seasons with an average annual temperature of 53°F (12°C). Winters average 27°F in January while summers reach 76°F in July. The area gets 293 sunny days per year, well above the U.S. average of 205 / making it one of the sunnier locations in the country. Annual precipitation totals 40.4 inches. The area receives 13.6 inches of snow annually. Air quality is rated Good with a median AQI of 43. The city sits at an elevation of 689 feet.

Temperature

27°F Jan (-3°C) 76°F Jul (24°C)

Annual Average	53.0°F
	2% below US avg
January Average	27°F (-3°C)
July Average	76°F (24°C)
Sunny Days	293 days/yr

Geography

Elevation	689 ft (210 m)
Area	46.9 sq mi (121.5 km²)
Population Density	1,610/sq mi
Coordinates	39.8560°N, 88.9337°W
Timezone	America/Chicago
County	Macon County County
Nearest Airport	Central Il Regional/Bloomington-Normal (BMI) 43 miles away

Precipitation & Snow

Annual Rainfall 40.4"

6% above US avg

Snowfall 13.6"

Wettest Month (May) 4.33"

Driest Month (Jan) 1.85"

Air Quality

AQI Median	43.0
Rating	Good

Natural Hazard Risk

Overall Risk	Relatively Moderate
Risk Score	83.3 / 100
Social Vulnerability	50.8 / 100
Community Resilience	91.0 / 100

Hazard Breakdown

Tornado	Relatively Moderate
Hurricane	Very Low
Earthquake	Relatively Low
Wildfire	Very Low
Flood	Relatively Moderate
Hail	Relatively Moderate
Strong Wind	Relatively High
Heat Wave	Relatively Moderate
Winter Weather	Relatively Moderate
Lightning	Relatively Moderate
Ice Storm	Relatively Moderate
Drought	Relatively Moderate
Cold Wave	Relatively High
Landslide	Very Low

Source: FEMA National Risk Index v1.20 (Dec 2025)

Earthquake History

10 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M3.8.

Jun 17, 2021	Illinois-Indiana border region	M3.8	141 km	6 km
Nov 11, 1991	3 km W of Flat Rock, Illinois	M3.8	149 km	0 km
Mar 2, 1990	9 km NW of Vernon, Illinois	M3.4	114 km	0 km
May 13, 2025	7 km SSW of Lerna, Illinois	M3.3	76 km	10 km
Jan 29, 1993	7 km WNW of Brownstown, Illinois	M3.2	92 km	5 km
Jul 1, 2017	9 km SSE of Mulberry Grove, Illinois	M3.1	115 km	17 km
Dec 16, 1996	3 km NNE of Terre Haute, Indiana	M3.1	137 km	5 km
Sep 5, 2004	3 km WNW of Saint Peter, Illinois	M2.9	108 km	33 km
Apr 24, 1990	5 km SW of Newton, Illinois	M2.9	118 km	18 km
Mar 15, 2025	6 km W of Dwight, Illinois	M2.6	142 km	5 km

Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.

Tornado History

795 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF4. Total: 24 fatalities, 663 injuries.

Date	Rating	Distance	Path	Fatalities
May 5, 1977	EF4	51 km	7.3 mi	0
Mar 20, 1976	EF4	13 km	63.7 mi	0
Jun 14, 1957	EF4	67 km	4.3 mi	2
Dec 1, 2018	EF3	63 km	12.5 mi	0
Nov 17, 2013	EF3	52 km	18.7 mi	0
Nov 17, 2013	EF3	78 km	29.8 mi	0
Apr 19, 2011	EF3	89 km	4.3 mi	0
Dec 31, 2010	EF3	80 km	3.6 mi	0
Aug 19, 2009	EF3	55 km	24.3 mi	0
May 10, 2003	EF3	93 km	17.5 mi	0
Jun 1, 1999	EF3	87 km	10.0 mi	1
Apr 19, 1996	EF3	89 km	2.0 mi	1
Apr 19, 1996	EF3	21 km	14.5 mi	0
Apr 19, 1996	EF3	63 km	9.4 mi	0
Apr 19, 1996	EF3	63 km	4.0 mi	0
May 9, 1995	EF3	68 km	50.0 mi	0
Jul 26, 1978	EF3	73 km	8.9 mi	0
Aug 21, 1977	EF3	53 km	26.9 mi	6
Aug 6, 1977	EF3	72 km	4.1 mi	0
Mar 20, 1976	EF3	80 km	8.8 mi	0

Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).

Monthly Weather

Month	Avg Temperature	Precipitation	Summary
January	27°F (-3°C)	1.9 in	Coldest, Driest
February	30°F (-1°C)	1.9 in
March	41°F (5°C)	3.3 in
April	53°F (11°C)	3.9 in
May	63°F (17°C)	4.3 in	Wettest
June	72°F (22°C)	3.9 in
July	76°F (24°C)	4.3 in	Warmest
August	74°F (23°C)	3.8 in
September	67°F (19°C)	3.2 in
October	55°F (13°C)	2.8 in
November	42°F (6°C)	3.2 in
December	31°F (-1°C)	2.9 in

Decatur has a seasonal temperature swing of 49°F / from 27°F in January to 76°F in July. Total annual precipitation is 39.2 inches, with May being the wettest month (4.3") and January the driest (1.9").

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