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Weather & Climate in Alpha, IL
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Alpha experiences four distinct seasons with an average annual temperature of 49°F (9°C). Winters average 21°F in January while summers reach 73°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 39.4 inches. Air quality is rated Good with a median AQI of 43. The city sits at an elevation of 803 feet.
Temperature
21°F Jan (-6°C)
73°F Jul (23°C)
| Annual Average | 49.0°F |
| 9% below US avg | |
| January Average | 21°F (-6°C) |
| July Average | 73°F (23°C) |
| Sunny Days | 275 days/yr |
Geography
| Elevation | 803 ft (245 m) |
| Area | 0.1 sq mi (0.3 km²) |
| Population Density | 2,584/sq mi |
| Coordinates | 41.1917°N, 90.3805°W |
| Timezone | America/Chicago |
| County | Henry County County |
| Nearest Airport | Quad Cities International (MLI) 19 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 43.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively Low |
| Risk Score | 57.1 / 100 |
| Social Vulnerability | 14.8 / 100 |
| Community Resilience | 83.8 / 100 |
Hazard Breakdown
| Tornado | Relatively Moderate |
| Hurricane | Very Low |
| Earthquake | Very Low |
| Wildfire | Very Low |
| Flood | Relatively Low |
| Hail | Relatively Moderate |
| Strong Wind | Relatively High |
| Heat Wave | Relatively Low |
| Winter Weather | Relatively Moderate |
| Lightning | Relatively Moderate |
| Ice Storm | Relatively Moderate |
| Drought | Relatively High |
| Cold Wave | Relatively Low |
| 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 | 127 km | 10 km |
| Sep 2, 1999 | 8 km W of Amboy, Illinois | M3.5 | 99 km | 5 km |
| Jul 15, 2024 | 2 km WNW of Somonauk, Illinois | M3.1 | 148 km | 10 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
672 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF4. Total: 19 fatalities, 532 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Nov 17, 2013 | EF4 | 93 km | 46.4 mi | 3 |
| Jul 13, 2004 | EF4 | 98 km | 9.6 mi | 0 |
| May 13, 1995 | EF4 | 92 km | 7.0 mi | 0 |
| Mar 29, 1981 | EF4 | 65 km | 5.1 mi | 0 |
| Jun 29, 1976 | EF4 | 69 km | 4.9 mi | 0 |
| Apr 11, 1965 | EF4 | 86 km | 91.5 mi | 1 |
| Apr 4, 2023 | EF3 | 96 km | 19.9 mi | 0 |
| Feb 28, 2017 | EF3 | 91 km | 17.8 mi | 0 |
| Jun 1, 2007 | EF3 | 68 km | 15.8 mi | 0 |
| Apr 20, 2004 | EF3 | 92 km | 15.8 mi | 8 |
| May 10, 2003 | EF3 | 100 km | 17.5 mi | 0 |
| May 13, 1995 | EF3 | 94 km | 25.0 mi | 0 |
| May 9, 1995 | EF3 | 50 km | 22.0 mi | 0 |
| May 9, 1995 | EF3 | 59 km | 10.0 mi | 0 |
| Mar 13, 1990 | EF3 | 46 km | 15.5 mi | 0 |
| May 8, 1988 | EF3 | 70 km | 32.0 mi | 0 |
| Aug 15, 1978 | EF3 | 35 km | 6.4 mi | 0 |
| Mar 4, 1976 | EF3 | 68 km | 0.8 mi | 0 |
| Jul 23, 1975 | EF3 | 72 km | 11.1 mi | 0 |
| Jul 23, 1975 | EF3 | 71 km | 14.0 mi | 2 |
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 | 60 km |
| 2002 | HSB 03 2 | 1,130 | 61 km |
| 2000 | DESTRUST A | 756 | 61 km |
| 2006 | HSB 003 | 674 | 60 km |
| 2004 | HSB 009 | 608 | 61 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 21°F (-6°C) | 1.5 in | Coldest |
| February | 26°F (-3°C) | 1.3 in | Driest |
| March | 38°F (3°C) | 2.8 in | |
| April | 50°F (10°C) | 3.8 in | |
| May | 61°F (16°C) | 4.1 in | |
| June | 71°F (22°C) | 4.3 in | |
| July | 73°F (23°C) | 4.5 in | Warmest, Wettest |
| August | 72°F (22°C) | 4.1 in | |
| September | 64°F (18°C) | 3.8 in | |
| October | 53°F (11°C) | 2.9 in | |
| November | 39°F (4°C) | 2.6 in | |
| December | 26°F (-3°C) | 2.1 in |
Alpha has a seasonal temperature swing of 51°F / from 21°F in January to 73°F in July. Total annual precipitation is 37.7 inches, with July being the wettest month (4.5") and February the driest (1.3").