Weather & Climate in Mount Vernon, IL

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

Mount Vernon experiences four distinct seasons with an average annual temperature of 55°F (13°C). Winters average 30°F in January while summers reach 77°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 45.0 inches. The area receives 10.4 inches of snow annually. Air quality is rated Good with a median AQI of 43. The city sits at an elevation of 523 feet.

Temperature

30°F Jan (-1°C) 77°F Jul (25°C)

Annual Average	54.5°F
	1% above US avg
January Average	30°F (-1°C)
July Average	77°F (25°C)
Sunny Days	293 days/yr

Geography

Elevation	523 ft (159 m)
Area	13.2 sq mi (34.1 km²)
Population Density	989/sq mi
Coordinates	38.3142°N, 88.9175°W
Timezone	America/Chicago
County	Jefferson County County
Nearest Airport	St Louis Regional (ALN) 73 miles away

Precipitation & Snow

Annual Rainfall 45.0"

18% above US avg

Snowfall 10.4"

Wettest Month (May) 4.49"

Driest Month (Jan) 2.40"

Air Quality

AQI Median	43.0
Rating	Good

Natural Hazard Risk

Overall Risk	Relatively Low
Risk Score	77.2 / 100
Social Vulnerability	52.8 / 100
Community Resilience	79.1 / 100

Hazard Breakdown

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

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

Earthquake History

94 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M5.2.

Apr 18, 2008	7 km NNE of Bellmont, Illinois	M5.2	91 km	14 km
Sep 26, 1990	4 km SE of Chaffee, Missouri	M4.8	143 km	1 km
Apr 18, 2008	9 km NNE of Bellmont, Illinois	M4.7	93 km	15 km
Jun 18, 2002	6 km SW of Parkers Settlement, Indiana	M4.6	107 km	16 km
Feb 5, 1994	2 km WNW of Dongola, Illinois	M4.2	108 km	16 km
Apr 21, 2008	7 km NNE of Bellmont, Illinois	M4.0	92 km	18 km
Dec 7, 2000	7 km W of Evansville, Indiana	M3.9	118 km	5 km
Nov 11, 1991	3 km W of Flat Rock, Illinois	M3.8	124 km	0 km
Sep 19, 2017	4 km N of Bellmont, Illinois	M3.8	89 km	12 km
Apr 25, 2008	8 km NNE of Bellmont, Illinois	M3.7	92 km	13 km
Nov 20, 2012	7 km N of Bellmont, Illinois	M3.6	90 km	19 km
Jan 2, 2006	3 km NNE of Eldorado, Illinois	M3.6	68 km	7 km
May 1, 2016	5 km SE of New Grand Chain, Illinois	M3.5	123 km	16 km
Jun 5, 2008	8 km WNW of Mount Carmel, Illinois	M3.4	95 km	16 km
Mar 2, 1990	9 km NW of Vernon, Illinois	M3.4	64 km	0 km
May 30, 2015	4 km ENE of Geff, Illinois	M3.4	52 km	26 km
May 1, 2008	8 km NNE of Bellmont, Illinois	M3.3	94 km	14 km
Aug 27, 1993	5 km SSE of Olympian Village, Missouri	M3.3	135 km	22 km
May 13, 2025	7 km SSW of Lerna, Illinois	M3.3	127 km	10 km
Apr 6, 1994	2 km NE of Tamaroa, Illinois	M3.2	31 km	15 km

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

Tornado History

515 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF5. Total: 65 fatalities, 954 injuries.

Date	Rating	Distance	Path	Fatalities
Dec 18, 1957	EF5	39 km	5.4 mi	1
Nov 17, 2013	EF4	48 km	10.6 mi	2
Feb 29, 2012	EF4	73 km	26.1 mi	8
Jun 2, 1990	EF4	90 km	12.5 mi	0
Jun 2, 1990	EF4	48 km	23.0 mi	0
Jun 2, 1990	EF4	40 km	106.0 mi	1
May 29, 1982	EF4	60 km	17.0 mi	10
Dec 18, 1957	EF4	84 km	28.3 mi	11
Dec 18, 1957	EF4	15 km	16.8 mi	1
May 26, 2024	EF3	82 km	4.9 mi	0
Mar 31, 2023	EF3	99 km	40.9 mi	6
Feb 28, 2017	EF3	73 km	44.1 mi	1
Apr 21, 2002	EF3	17 km	31.5 mi	1
Apr 19, 1996	EF3	23 km	17.0 mi	0
Nov 19, 1991	EF3	65 km	1.5 mi	0
Dec 2, 1982	EF3	72 km	10.5 mi	2
May 29, 1982	EF3	73 km	10.0 mi	0
Jul 28, 1976	EF3	87 km	0.1 mi	0
Apr 18, 1975	EF3	95 km	2.0 mi	0
Apr 21, 1972	EF3	92 km	0.3 mi	3

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

Wildfire History

20 wildfires (100+ acres) recorded within 100 km. Largest: RED SHALE UNIT RX (2,123 acres, 2021).

Year	Name	Acres Burned	Distance
2021	RED SHALE UNIT RX	2,123	72 km
2021	GAP VIEW RX	1,575	95 km
2022	DENNISON HOLLOW RX	1,573	85 km
2021	UNNAMED	1,510	94 km
2022	ONE HORSE GAP RX	1,502	98 km
2014	UNNAMED	1,493	84 km
2015	UNNAMED	1,447	86 km
2016	UNNAMED	1,299	98 km
2024	RED SHALE RX	1,259	73 km
2014	UNNAMED	1,216	99 km
2019	KINKAID RX	1,215	72 km
2013	UNNAMED	1,203	98 km
2022	KINKAID STATE FISH AND WILDLIFE AREA RX	1,115	72 km
2021	STATE OF ILLINOIS TRACT RX	1,011	74 km
2015	UNNAMED	1,008	97 km
2024	CAVE HILL RX	999	84 km
2017	UNNAMED	994	86 km
2021	MILL CREEK RX	898	84 km
2021	ONE HORSE GAP RX	865	97 km
2024	HAMPTON NORTH RX	807	70 km

Source: NIFC/IRWIN Wildfire Records (100+ acres).

Monthly Weather

Month	Avg Temperature	Precipitation	Summary
January	30°F (-1°C)	2.4 in	Coldest, Driest
February	34°F (1°C)	2.6 in
March	45°F (7°C)	4.2 in
April	55°F (13°C)	4.2 in
May	65°F (18°C)	4.5 in	Wettest
June	74°F (23°C)	3.8 in
July	77°F (25°C)	3.6 in	Warmest
August	76°F (24°C)	3.2 in
September	69°F (21°C)	3.1 in
October	57°F (14°C)	3.0 in
November	46°F (8°C)	4.1 in
December	35°F (2°C)	3.4 in

Mount Vernon has a seasonal temperature swing of 46°F / from 30°F in January to 77°F in July. Total annual precipitation is 42.1 inches, with May being the wettest month (4.5") and January the driest (2.4").

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