Weather & Climate in Rio, IL
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Rio experiences four distinct seasons with an average annual temperature of 50°F (10°C). Winters average 22°F in January while summers reach 75°F in July. Annual precipitation totals 37.4 inches. The area receives 26.8 inches of snow annually, a moderate snowfall amount. The city sits at an elevation of 779 feet.
Temperature
22°F Jan (-6°C)
75°F Jul (24°C)
| Annual Average | 50.2°F |
| 7% below US avg | |
| January Average | 22°F (-6°C) |
| July Average | 75°F (24°C) |
Geography
| Elevation | 779 ft (237 m) |
| Area | 0.1 sq mi (0.3 km²) |
| Population Density | 677/sq mi |
| Coordinates | 41.1093°N, 90.3988°W |
| Timezone | America/Chicago |
| County | Mercer County County |
| Nearest Airport | Quad Cities International (MLI) 24 miles away |
Precipitation & Snow
Air Quality
Natural Hazard Risk
| Overall Risk | Very Low |
| Risk Score | 8.8 / 100 |
| Social Vulnerability | 10.6 / 100 |
| Community Resilience | 85.7 / 100 |
Hazard Breakdown
| Tornado | Very Low |
| Hurricane | Very Low |
| Earthquake | Very Low |
| Wildfire | Very Low |
| Flood | Very Low |
| Hail | Very Low |
| Strong Wind | Relatively Moderate |
| Heat Wave | Relatively Low |
| Winter Weather | Relatively Low |
| Lightning | Relatively Moderate |
| Ice Storm | Relatively Moderate |
| Drought | Relatively Moderate |
| Cold Wave | Relatively Low |
| Landslide | Relatively Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
2 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M4.2.
| Jun 28, 2004 | 12 km NW of Dayton, Illinois | M4.2 | 131 km | 10 km |
| Sep 2, 1999 | 8 km W of Amboy, Illinois | M3.5 | 105 km | 5 km |
Source: USGS Earthquake Catalog (M2.5+, 1990-2025). Sorted by magnitude.
Tornado History
678 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF4. Total: 20 fatalities, 545 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Nov 17, 2013 | EF4 | 88 km | 46.4 mi | 3 |
| Jul 13, 2004 | EF4 | 96 km | 9.6 mi | 0 |
| May 13, 1995 | EF4 | 83 km | 7.0 mi | 0 |
| May 13, 1995 | EF4 | 97 km | 50.0 mi | 0 |
| Mar 29, 1981 | EF4 | 74 km | 5.1 mi | 0 |
| Jun 29, 1976 | EF4 | 64 km | 4.9 mi | 0 |
| Apr 11, 1965 | EF4 | 94 km | 91.5 mi | 1 |
| Apr 4, 2023 | EF3 | 87 km | 19.9 mi | 0 |
| Feb 28, 2017 | EF3 | 90 km | 17.8 mi | 0 |
| Jun 1, 2007 | EF3 | 69 km | 15.8 mi | 0 |
| Apr 20, 2004 | EF3 | 95 km | 15.8 mi | 8 |
| May 10, 2003 | EF3 | 93 km | 17.5 mi | 0 |
| May 13, 1995 | EF3 | 86 km | 25.0 mi | 0 |
| May 9, 1995 | EF3 | 66 km | 10.0 mi | 0 |
| May 9, 1995 | EF3 | 54 km | 22.0 mi | 0 |
| Mar 13, 1990 | EF3 | 56 km | 15.5 mi | 0 |
| May 8, 1988 | EF3 | 78 km | 32.0 mi | 0 |
| Jun 21, 1981 | EF3 | 100 km | 8.8 mi | 1 |
| Aug 15, 1978 | EF3 | 37 km | 6.4 mi | 0 |
| Mar 4, 1976 | EF3 | 70 km | 0.8 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950-2024, US only).
Wildfire History
5 wildfires (100+ acres) recorded within 100 km. Largest: UNIT 3 (1,206 acres, 1999).
| Year | Name | Acres Burned | Distance |
| 1999 | UNIT 3 | 1,206 | 58 km |
| 2002 | HSB 03 2 | 1,130 | 59 km |
| 2000 | DESTRUST A | 756 | 59 km |
| 2006 | HSB 003 | 674 | 58 km |
| 2004 | HSB 009 | 608 | 59 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 22°F (-6°C) | 1.7 in | Coldest, Driest |
| February | 26°F (-3°C) | 1.9 in | |
| March | 38°F (3°C) | 2.4 in | |
| April | 51°F (10°C) | 3.7 in | |
| May | 62°F (17°C) | 4.8 in | Wettest |
| June | 72°F (22°C) | 4.1 in | |
| July | 75°F (24°C) | 3.9 in | Warmest |
| August | 73°F (23°C) | 3.5 in | |
| September | 66°F (19°C) | 3.5 in | |
| October | 53°F (12°C) | 2.9 in | |
| November | 39°F (4°C) | 2.8 in | |
| December | 28°F (-2°C) | 2.2 in |
Rio has a seasonal temperature swing of 53°F / from 22°F in January to 75°F in July. Total annual precipitation is 37.4 inches, with May being the wettest month (4.8") and January the driest (1.7").