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Waterloo, IL
Full City Profile · Illinois · Monroe County County
3.7
/5.0
B+
Good
11,055
Population
1,334/sq mi density
$92,005
Median Income
$44,435 per capita
$237,900
Home Value
$321,639 Zillow
$873
Median Rent
27.7% income on rent
56°F
Avg Temperature
293 sunny days/yr
89
Violent Crime/100K
993 property/100K
B+
Overall
3.7 / 5.0
Good overall score based on economy, affordability, safety and education
A+
Economy
4.8 / 5.0
$92,005 median income, 2.2% unemployment
A+
Affordability
5.0 / 5.0
$237,900 home value, $873/mo rent
F
Safety
1.0 / 5.0
89 violent crimes/100K
B+
Education
3.9 / 5.0
36.4% bachelor's degree or higher
Waterloo enjoys a temperate climate with an average annual temperature of 56°F (13°C). Winters average 32°F in January while summers reach 78°F in July. The area gets 293 sunny days per year. Annual precipitation totals 43.6 inches. The area receives 9.2 inches of snow annually. Air quality is rated Good with a median AQI of 43.
Temperature
32°F Jan (-0°C)
78°F Jul (25°C)
| Annual Average | 55.7°F |
| 3% above US avg | |
| January Average | 32°F (-0°C) |
| July Average | 78°F (25°C) |
| Sunny Days | 293 days/yr |
Geography
| Elevation | 694 ft (212 m) |
| Area | 7.7 sq mi (19.8 km²) |
| Population Density | 1,334/sq mi |
| Coordinates | 38.3412°N, 90.1527°W |
| Timezone | America/Chicago |
| County | Monroe County County |
| Nearest Airport | St Louis Lambert International (STL) 31 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 43.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Very Low |
| Risk Score | 41.9 / 100 |
| Social Vulnerability | 10.6 / 100 |
| Community Resilience | 94.9 / 100 |
Hazard Breakdown
| Tornado | Relatively Low |
| Hurricane | Very Low |
| Earthquake | Relatively Low |
| Wildfire | Very Low |
| Flood | Very Low |
| Hail | Relatively Low |
| Strong Wind | Relatively Moderate |
| Heat Wave | Relatively Moderate |
| Winter Weather | Relatively Low |
| Lightning | Relatively Low |
| Ice Storm | Very Low |
| Drought | Relatively Low |
| Cold Wave | Relatively Low |
| Landslide | Relatively Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 32°F (-0°C) | 2.1 in | Coldest, Driest |
| February | 34°F (1°C) | 2.3 in | |
| March | 44°F (7°C) | 3.6 in | |
| April | 55°F (13°C) | 3.7 in | |
| May | 65°F (18°C) | 4.1 in | Wettest |
| June | 74°F (23°C) | 3.7 in | |
| July | 78°F (25°C) | 3.8 in | Warmest |
| August | 76°F (24°C) | 3.2 in | |
| September | 69°F (20°C) | 3.4 in | |
| October | 57°F (14°C) | 2.8 in | |
| November | 45°F (7°C) | 3.5 in | |
| December | 34°F (1°C) | 3.1 in |
Waterloo has a seasonal temperature swing of 46°F / from 32°F in January to 78°F in July. Total annual precipitation is 39.2 inches, with May being the wettest month (4.1") and January the driest (2.1").