Waterloo, IL
Full City Profile · Illinois · Monroe County County
4.5
/5.0
A+
Excellent
11,055
Population
1,334/sq mi density
$92,005
Median Income
$44,435 per capita
$237,900
Home Value
$331,438 Zillow
$873
Median Rent
27.7% income on rent
57°F
Avg Temperature
A+
Overall
4.5 / 5.0
Strong
A+
Economy
4.6 / 5.0
$92,005 median income, 3.4% unemployment
A+
Affordability
5.0 / 5.0
$237,900 home value, $873/mo rent
B+
Education
3.9 / 5.0
36.4% bachelor's degree or higher
Waterloo enjoys a temperate climate with an average annual temperature of 57°F (14°C). Winters average 32°F in January while summers reach 79°F in July. Annual precipitation totals 45.1 inches. The area receives 8.8 inches of snow annually.
Temperature
32°F Jan (0°C)
79°F Jul (26°C)
| Annual Average | 56.5°F |
| 5% above US avg | |
| January Average | 32°F (0°C) |
| July Average | 79°F (26°C) |
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
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) | 2.9 in | Coldest |
| February | 37°F (3°C) | 2.5 in | Driest |
| March | 46°F (8°C) | 3.4 in | |
| April | 57°F (14°C) | 5.0 in | Wettest |
| May | 67°F (19°C) | 4.9 in | |
| June | 75°F (24°C) | 4.7 in | |
| July | 79°F (26°C) | 5.0 in | Warmest |
| August | 77°F (25°C) | 3.4 in | |
| September | 69°F (21°C) | 3.9 in | |
| October | 58°F (14°C) | 3.2 in | |
| November | 46°F (8°C) | 3.3 in | |
| December | 36°F (2°C) | 3.0 in |
Waterloo has a seasonal temperature swing of 47°F / from 32°F in January to 79°F in July. Total annual precipitation is 45.1 inches, with April being the wettest month (5.0") and February the driest (2.5").