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Weather & Climate in Port Byron, IL
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Port Byron experiences four distinct seasons with an average annual temperature of 51°F (10°C). Winters average 22°F in January while summers reach 76°F in July. The area gets 275 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 37.1 inches. Air quality is rated Good with a median AQI of 43. The city sits at an elevation of 625 feet.
Temperature
22°F Jan (-5°C)
76°F Jul (24°C)
| Annual Average | 50.6°F |
| 6% below US avg | |
| January Average | 22°F (-5°C) |
| July Average | 76°F (24°C) |
| Sunny Days | 275 days/yr |
Geography
| Elevation | 625 ft (191 m) |
| Area | 2.4 sq mi (6.3 km²) |
| Population Density | 806/sq mi |
| Coordinates | 41.6243°N, 90.3302°W |
| Timezone | America/Chicago |
| County | Scott County County |
| Nearest Airport | Quad Cities International (MLI) 15 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 43.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively Moderate |
| Risk Score | 84.9 / 100 |
| Social Vulnerability | 19.2 / 100 |
| Community Resilience | 95.9 / 100 |
Hazard Breakdown
| Tornado | Relatively Moderate |
| Hurricane | Very Low |
| Earthquake | Relatively Low |
| Wildfire | Very Low |
| Flood | Relatively Moderate |
| Hail | Relatively High |
| Strong Wind | Relatively High |
| Heat Wave | Relatively Moderate |
| Winter Weather | Relatively High |
| Lightning | Relatively High |
| Ice Storm | Relatively High |
| Drought | Relatively Moderate |
| Cold Wave | Relatively Moderate |
| Landslide | Relatively Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
3 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 | 120 km | 10 km |
| Sep 2, 1999 | 8 km W of Amboy, Illinois | M3.5 | 75 km | 5 km |
| Jul 15, 2024 | 2 km WNW of Somonauk, Illinois | M3.1 | 135 km | 10 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
629 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF4. Total: 17 fatalities, 173 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Apr 9, 2015 | EF4 | 90 km | 30.1 mi | 2 |
| Mar 29, 1981 | EF4 | 32 km | 5.1 mi | 0 |
| Apr 11, 1965 | EF4 | 56 km | 91.5 mi | 1 |
| Jun 1, 2007 | EF3 | 82 km | 15.8 mi | 0 |
| Apr 20, 2004 | EF3 | 97 km | 15.8 mi | 8 |
| May 9, 1995 | EF3 | 57 km | 22.0 mi | 0 |
| May 9, 1995 | EF3 | 45 km | 10.0 mi | 0 |
| Jun 19, 1993 | EF3 | 84 km | 14.0 mi | 0 |
| Jul 13, 1992 | EF3 | 91 km | 5.0 mi | 0 |
| Mar 13, 1990 | EF3 | 5 km | 15.5 mi | 0 |
| May 8, 1988 | EF3 | 40 km | 32.0 mi | 0 |
| Aug 5, 1979 | EF3 | 76 km | 5.7 mi | 0 |
| Aug 15, 1978 | EF3 | 54 km | 6.4 mi | 0 |
| Mar 4, 1976 | EF3 | 79 km | 0.8 mi | 0 |
| Jun 20, 1974 | EF3 | 40 km | 10.6 mi | 1 |
| Jun 14, 1974 | EF3 | 39 km | 48.6 mi | 0 |
| May 13, 1974 | EF3 | 22 km | 3.6 mi | 0 |
| Jul 17, 1972 | EF3 | 85 km | 81.5 mi | 0 |
| Jan 24, 1967 | EF3 | 54 km | 7.4 mi | 0 |
| Apr 19, 1966 | EF3 | 20 km | 2.0 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 | 85 km |
| 2002 | HSB 03 2 | 1,130 | 86 km |
| 2000 | DESTRUST A | 756 | 85 km |
| 2006 | HSB 003 | 674 | 86 km |
| 2004 | HSB 009 | 608 | 85 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 22°F (-5°C) | 1.4 in | Coldest |
| February | 26°F (-4°C) | 1.3 in | Driest |
| March | 37°F (3°C) | 2.6 in | |
| April | 50°F (10°C) | 3.7 in | |
| May | 61°F (16°C) | 4.1 in | |
| June | 70°F (21°C) | 4.4 in | Wettest |
| July | 76°F (24°C) | 4.2 in | Warmest |
| August | 72°F (22°C) | 4.3 in | |
| September | 64°F (18°C) | 3.6 in | |
| October | 53°F (11°C) | 2.8 in | |
| November | 38°F (4°C) | 2.5 in | |
| December | 26°F (-3°C) | 2.0 in |
Port Byron has a seasonal temperature swing of 53°F / from 22°F in January to 76°F in July. Total annual precipitation is 36.8 inches, with June being the wettest month (4.4") and February the driest (1.3").