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Alton, IL
Full City Profile · Illinois · St. Louis city County
3.0
/5.0
B
Good
25,430
Population
1,623/sq mi density
$53,005
Median Income
$28,970 per capita
$99,500
Home Value
$100,385 Zillow
$948
Median Rent
31.4% income on rent
56°F
Avg Temperature
293 sunny days/yr
1,017
Violent Crime/100K
4,177 property/100K
B
Overall
3.0 / 5.0
Good overall score based on economy, affordability, safety and education
B
Economy
3.3 / 5.0
$53,005 median income, 3.1% unemployment
A+
Affordability
5.0 / 5.0
$99,500 home value, $948/mo rent
F
Safety
1.0 / 5.0
1,017 violent crimes/100K (168% above avg)
C+
Education
2.7 / 5.0
21.2% bachelor's degree or higher
Alton enjoys a temperate climate with an average annual temperature of 56°F (13°C). Winters average 30°F in January while summers reach 78°F in July. The area gets 293 sunny days per year. Annual precipitation totals 41.9 inches. Air quality is rated Good with a median AQI of 43.
Temperature
30°F Jan (-1°C)
78°F Jul (26°C)
| Annual Average | 55.7°F |
| 3% above US avg | |
| January Average | 30°F (-1°C) |
| July Average | 78°F (26°C) |
| Sunny Days | 293 days/yr |
Geography
| Elevation | 532 ft (162 m) |
| Area | 16.7 sq mi (43.4 km²) |
| Population Density | 1,623/sq mi |
| Coordinates | 38.9039°N, 90.1512°W |
| Timezone | America/Chicago |
| County | St. Louis city County |
| Nearest Airport | St Louis Regional (ALN) 6 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 43.0 |
| Rating | Good |
Air Pollutants (EPA 2023)
| Ozone (O₃) | 0.0419 ppm |
| NO₂ (Nitrogen Dioxide) | 15.1 ppb |
| SO₂ (Sulfur Dioxide) | 1.03 ppb |
| CO (Carbon Monoxide) | 0.28 ppm |
| PM2.5 (Fine Particles) | 10.1 μg/m³ |
Natural Hazard Risk
| Overall Risk | Relatively High |
| Risk Score | 98.7 / 100 |
| Social Vulnerability | 71.9 / 100 |
| Community Resilience | 61.0 / 100 |
Hazard Breakdown
| Tornado | Very High |
| Hurricane | Very Low |
| Earthquake | Relatively High |
| Wildfire | Very Low |
| Flood | Relatively High |
| Hail | Relatively Moderate |
| Strong Wind | Relatively High |
| Heat Wave | Very High |
| Winter Weather | Relatively Moderate |
| Lightning | Relatively High |
| Ice Storm | Relatively High |
| Drought | No Rating |
| Cold Wave | Relatively Moderate |
| Landslide | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 30°F (-1°C) | 1.9 in | Coldest, Driest |
| February | 33°F (0°C) | 2.1 in | |
| March | 43°F (6°C) | 3.4 in | |
| April | 55°F (13°C) | 3.7 in | |
| May | 64°F (18°C) | 4.1 in | Wettest |
| June | 73°F (23°C) | 3.7 in | |
| July | 78°F (26°C) | 3.7 in | Warmest |
| August | 76°F (24°C) | 3.4 in | |
| September | 68°F (20°C) | 3.3 in | |
| October | 57°F (14°C) | 2.8 in | |
| November | 44°F (7°C) | 3.3 in | |
| December | 33°F (0°C) | 3.0 in |
Alton has a seasonal temperature swing of 48°F / from 30°F in January to 78°F in July. Total annual precipitation is 38.2 inches, with May being the wettest month (4.1") and January the driest (1.9").