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Weather & Climate in Ontario, WI

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

Ontario experiences four distinct seasons with an average annual temperature of 46°F (8°C). Winters average 17°F in January while summers reach 72°F in July. The area gets 260 sunny days per year, above the national average. Annual precipitation totals 35.0 inches. The area receives 54.5 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 870 feet.

Temperature

17°F Jan (-8°C) 72°F Jul (22°C)
Annual Average46.2°F
14% below US avg
January Average17°F (-8°C)
July Average72°F (22°C)
Sunny Days260 days/yr

Geography

Elevation870 ft (265 m)
Area1.0 sq mi (2.6 km²)
Population Density380/sq mi
Coordinates43.7219°N, 90.5932°W
TimezoneAmerica/Chicago
CountyVernon County County
Nearest AirportLa Crosse Regional (LSE)
35 miles away

Precipitation & Snow

Annual Rainfall 35.0"
8% below US avg
Snowfall 54.5"
Wettest Month (Aug) 4.25"
Driest Month (Jan) 0.91"

Air Quality

AQI Median38.0
RatingGood

Natural Hazard Risk

Overall RiskRelatively Low
Risk Score75.0 / 100
Social Vulnerability79.4 / 100
Community Resilience65.0 / 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 High
Landslide Relatively High
Source: FEMA National Risk Index v1.20 (Dec 2025)

Tornado History

306 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF5. Total: 15 fatalities, 435 injuries.

Date Rating Distance Path Fatalities
Jun 7, 1984 EF5 97 km 36.0 mi 9
Jul 3, 1983 EF4 92 km 0.5 mi 0
Apr 19, 1957 EF4 37 km 21.1 mi 1
Aug 7, 2021 EF3 67 km 9.4 mi 0
Aug 27, 1994 EF3 68 km 10.5 mi 2
Aug 29, 1992 EF3 94 km 28.0 mi 1
Jul 3, 1983 EF3 49 km 1.0 mi 0
Jun 5, 1980 EF3 51 km 26.9 mi 0
Sep 3, 1964 EF3 58 km 17.1 mi 0
Aug 16, 1963 EF3 85 km 9.6 mi 0
Aug 16, 1963 EF3 85 km 9.6 mi 0
Aug 16, 1963 EF3 85 km 9.6 mi 0
May 26, 1959 EF3 73 km 34.3 mi 0
Apr 19, 1957 EF3 13 km 9.0 mi 0
Jun 15, 2022 EF2 20 km 22.9 mi 0
Dec 15, 2021 EF2 89 km 3.1 mi 0
Dec 15, 2021 EF2 89 km 2.8 mi 0
Dec 15, 2021 EF2 97 km 1.1 mi 0
Jun 29, 2014 EF2 80 km 29.1 mi 0
Jun 29, 2014 EF2 89 km 5.1 mi 0
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).

Wildfire History

20 wildfires (100+ acres) recorded within 100 km. Largest: COTTONVILLE INCIDENT (3,466 acres, 2005).

Year Name Acres Burned Distance
2005 COTTONVILLE INCIDENT 3,466 80 km
1987 BIG BURN 3,154 59 km
2024 2024 DOD HARDWOOD RANGE RX 2,717 70 km
1994 BIG BURN 2,248 59 km
2023 2023 RX 1,992 70 km
1997 BIG BURN 1,642 60 km
2004 POOL ONE NORTH 1,576 52 km
1998 UNNAMED 1,297 60 km
2021 2021 DOD HARDWOOD RANGE RX 987 70 km
2007 UNNAMED 981 50 km
2003 UNNAMED 901 58 km
1998 PR 17 896 52 km
2007 UNNAMED 875 53 km
2009 UNNAMED 867 51 km
2007 PR 16 778 59 km
2006 PR 17 RX FIRE 701 60 km
2018 2018 BADGER RX BURNS 659 78 km
2005 UNNAMED 657 53 km
2003 PR 17 632 60 km
2019 2019 BADGER RX BURNS 627 79 km
Source: NIFC/IRWIN Wildfire Records (100+ acres).

Monthly Weather

Month Avg Temperature Precipitation Summary
January 17°F (-8°C) 0.9 in Coldest, Driest
February 19°F (-7°C) 0.9 in
March 31°F (-1°C) 1.9 in
April 44°F (7°C) 3.2 in
May 57°F (14°C) 3.5 in
June 66°F (19°C) 3.9 in
July 72°F (22°C) 4.1 in Warmest
August 68°F (20°C) 4.3 in Wettest
September 60°F (16°C) 4.1 in
October 49°F (9°C) 2.3 in
November 34°F (1°C) 2.1 in
December 20°F (-6°C) 1.3 in

Ontario has a seasonal temperature swing of 54°F / from 17°F in January to 72°F in July. Total annual precipitation is 32.5 inches, with August being the wettest month (4.3") and January the driest (0.9").

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