Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Monticello experiences four distinct seasons with an average annual temperature of 47°F (9°C). Winters average 19°F in January while summers reach 73°F in July. The area gets 260 sunny days per year, above the national average. Annual precipitation totals 39.7 inches. The area receives 41.5 inches of snow annually, making winter weather a significant factor for residents. Air quality is rated Good with a median AQI of 38. The city sits at an elevation of 834 feet.
Temperature
19°F Jan (-7°C)73°F Jul (23°C)
Annual Average
47.3°F
12% below US avg
January Average
19°F (-7°C)
July Average
73°F (23°C)
Sunny Days
260 days/yr
Geography
Elevation
834 ft (254 m)
Area
1.2 sq mi (3.1 km²)
Population Density
997/sq mi
Coordinates
42.7447°N, 89.5903°W
Timezone
America/Chicago
County
Green County County
Nearest Airport
Southern Wisconsin Regional (JVL) 29 miles away
Precipitation & Snow
Annual Rainfall39.7"
5% above US avg
Snowfall41.5"
Wettest Month (Aug)4.13"
Driest Month (Jan)1.14"
Air Quality
AQI Median
38.0
Rating
Good
Natural Hazard Risk
Overall Risk
Relatively Low
Risk Score
46.4 / 100
Social Vulnerability
17.8 / 100
Community Resilience
81.9 / 100
Hazard Breakdown
Tornado
Relatively Moderate
Hurricane
Very Low
Earthquake
Very Low
Wildfire
Very Low
Flood
Relatively Low
Hail
Relatively Moderate
Strong Wind
Relatively Moderate
Heat Wave
Relatively Low
Winter Weather
Relatively Low
Lightning
Relatively Low
Ice Storm
Relatively Low
Drought
Relatively Low
Cold Wave
Relatively Moderate
Landslide
Relatively Low
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
5 earthquakes (M2.5+) recorded within 150 km since 1990.
Strongest on record: M3.8.
Feb 10, 2010
2 km NW of Lily Lake, Illinois
M3.8
125 km
10 km
Sep 2, 1999
8 km W of Amboy, Illinois
M3.5
115 km
5 km
Jul 15, 2024
2 km WNW of Somonauk, Illinois
M3.1
142 km
10 km
Mar 25, 2015
3 km WNW of Lake in the Hills, Illinois
M2.9
118 km
6 km
Jun 10, 2013
4 km NNE of Virgil, Illinois
M2.6
122 km
5 km
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
530 tornadoes (EF0+) recorded within 100 km since 1950.
Strongest on record: EF5. Total: 44 fatalities, 1,018 injuries.
Date
Rating
Distance
Path
Fatalities
Jun 7, 1984
EF5
41 km
36.0 mi
9
Jul 3, 1983
EF4
51 km
0.5 mi
0
Apr 21, 1967
EF4
80 km
25.5 mi
24
Sep 26, 1951
EF4
85 km
9.0 mi
1
Jun 16, 2014
EF3
29 km
1.0 mi
0
Jan 7, 2008
EF3
74 km
13.2 mi
0
Aug 18, 2005
EF3
24 km
18.6 mi
1
Jun 17, 1992
EF3
16 km
16.0 mi
0
May 8, 1988
EF3
55 km
16.0 mi
0
Jun 8, 1984
EF3
84 km
29.0 mi
0
Jun 5, 1980
EF3
79 km
10.7 mi
0
Apr 7, 1980
EF3
96 km
1.2 mi
0
Aug 5, 1979
EF3
81 km
5.7 mi
0
Jun 4, 1975
EF3
61 km
2.3 mi
0
Sep 9, 1970
EF3
92 km
4.7 mi
0
Aug 2, 1967
EF3
44 km
0.1 mi
2
Apr 16, 1967
EF3
37 km
27.8 mi
0
Jan 24, 1967
EF3
24 km
24.9 mi
0
Jan 24, 1967
EF3
85 km
7.4 mi
0
Sep 3, 1964
EF3
99 km
17.1 mi
0
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Wildfire History
4 wildfires (100+ acres) recorded within 100 km.
Largest: 2018 BADGER RX BURNS (659 acres, 2018).
Year
Name
Acres Burned
Distance
2018
2018 BADGER RX BURNS
659
71 km
2019
2019 BADGER RX BURNS
627
71 km
2024
RX-HWY Y - SOUTH
553
73 km
2009
COLD SPRINGS
552
9 km
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
Month
Avg Temperature
Precipitation
Summary
January
19°F (-7°C)
1.1 in
Coldest, Driest
February
21°F (-6°C)
1.1 in
March
33°F (1°C)
2.2 in
April
46°F (8°C)
3.2 in
May
58°F (14°C)
3.5 in
June
67°F (19°C)
4.1 in
July
73°F (23°C)
3.9 in
Warmest
August
69°F (21°C)
4.1 in
Wettest
September
61°F (16°C)
3.8 in
October
49°F (10°C)
2.5 in
November
36°F (2°C)
2.2 in
December
23°F (-5°C)
1.7 in
Monticello has a seasonal temperature swing of 54°F / from 19°F in January to 73°F in July. Total annual precipitation is 33.6 inches, with August being the wettest month (4.1") and January the driest (1.1").