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Williamson, IL
Full City Profile · Illinois · Madison County County
2.8
/5.0
C+
Fair
164
Population
140/sq mi density
$56,667
Median Income
$32,270 per capita
$75,500
Home Value
$100,968 Zillow
$779
Median Rent
14.2% income on rent
58°F
Avg Temperature
293 sunny days/yr
138
Violent Crime/100K
1,320 property/100K
C+
Overall
2.8 / 5.0
Fair overall score based on economy, affordability, safety and education
B+
Economy
3.9 / 5.0
$56,667 median income, 0.0% unemployment
A+
Affordability
5.0 / 5.0
$75,500 home value, $779/mo rent
F
Safety
1.0 / 5.0
138 violent crimes/100K
F
Education
1.2 / 5.0
2.9% bachelor's degree or higher
Williamson enjoys a temperate climate with an average annual temperature of 58°F (14°C). Winters average 34°F in January while summers reach 79°F in July. The area gets 293 sunny days per year. Annual precipitation totals 43.4 inches. The area receives 11.2 inches of snow annually. Air quality is rated Good with a median AQI of 43.
Temperature
34°F Jan (1°C)
79°F Jul (26°C)
| Annual Average | 57.7°F |
| 7% above US avg | |
| January Average | 34°F (1°C) |
| July Average | 79°F (26°C) |
| Sunny Days | 293 days/yr |
Geography
| Elevation | 599 ft (183 m) |
| Area | 0.6 sq mi (1.6 km²) |
| Population Density | 140/sq mi |
| Coordinates | 38.9845°N, 89.7625°W |
| Timezone | America/Chicago |
| County | Madison County County |
| Nearest Airport | St Louis Regional (ALN) 17 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 43.0 |
| Rating | Good |
Air Pollutants (EPA 2023)
| Ozone (O₃) | 0.0502 ppm |
| SO₂ (Sulfur Dioxide) | 1.30 ppb |
| PM2.5 (Fine Particles) | 9.6 μg/m³ |
Natural Hazard Risk
| Overall Risk | Relatively Moderate |
| Risk Score | 93.4 / 100 |
| Social Vulnerability | 25.9 / 100 |
| Community Resilience | 86.2 / 100 |
Hazard Breakdown
| Tornado | Relatively High |
| Hurricane | Very Low |
| Earthquake | Relatively Moderate |
| Wildfire | Very Low |
| Flood | Relatively Moderate |
| Hail | Relatively High |
| Strong Wind | Relatively Moderate |
| Heat Wave | Relatively High |
| Winter Weather | Relatively High |
| Lightning | Relatively High |
| Ice Storm | Relatively Moderate |
| Drought | Relatively Low |
| Cold Wave | Relatively High |
| Landslide | Relatively Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 34°F (1°C) | 1.9 in | Driest |
| February | 32°F (0°C) | 2.1 in | Coldest |
| March | 43°F (6°C) | 3.5 in | |
| April | 54°F (12°C) | 3.8 in | |
| May | 64°F (18°C) | 4.2 in | Wettest |
| June | 73°F (23°C) | 3.9 in | |
| July | 79°F (26°C) | 3.6 in | Warmest |
| August | 75°F (24°C) | 3.2 in | |
| September | 68°F (20°C) | 3.2 in | |
| October | 56°F (14°C) | 2.8 in | |
| November | 44°F (7°C) | 3.4 in | |
| December | 33°F (0°C) | 3.0 in |
Williamson has a seasonal temperature swing of 47°F / from 32°F in February to 79°F in July. Total annual precipitation is 38.4 inches, with May being the wettest month (4.2") and January the driest (1.9").