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Marengo, IL
Full City Profile · Illinois · McHenry County County
2.9
/5.0
C+
Fair
7,123
Population
800/sq mi density
$72,586
Median Income
$35,638 per capita
$206,100
Home Value
$345,185 Zillow
$1,077
Median Rent
33.7% income on rent
48°F
Avg Temperature
260 sunny days/yr
173
Violent Crime/100K
933 property/100K
C+
Overall
2.9 / 5.0
Fair overall score based on economy, affordability, safety and education
B
Economy
3.3 / 5.0
$72,586 median income, 5.8% unemployment
A+
Affordability
5.0 / 5.0
$206,100 home value, $1,077/mo rent
F
Safety
1.0 / 5.0
173 violent crimes/100K
C
Education
2.3 / 5.0
16.5% bachelor's degree or higher
Marengo experiences four distinct seasons with an average annual temperature of 48°F (9°C). Winters average 21°F in January while summers reach 73°F in July. The area gets 260 sunny days per year. Annual precipitation totals 37.6 inches. The area receives 30.8 inches of snow annually. Air quality is rated Good with a median AQI of 43.
Temperature
21°F Jan (-6°C)
73°F Jul (23°C)
| Annual Average | 48.2°F |
| 11% below US avg | |
| January Average | 21°F (-6°C) |
| July Average | 73°F (23°C) |
| Sunny Days | 260 days/yr |
Geography
| Elevation | 822 ft (251 m) |
| Area | 8.9 sq mi (23.1 km²) |
| Population Density | 800/sq mi |
| Coordinates | 42.2466°N, 88.5975°W |
| Timezone | America/Chicago |
| County | McHenry County County |
| Nearest Airport | Chicago/Rockford International (RFD) 26 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 43.0 |
| Rating | Good |
Air Pollutants (EPA 2023)
| Ozone (O₃) | 0.0484 ppm |
| PM2.5 (Fine Particles) | 9.1 μg/m³ |
Natural Hazard Risk
| Overall Risk | Relatively Moderate |
| Risk Score | 90.8 / 100 |
| Social Vulnerability | 10.6 / 100 |
| Community Resilience | 84.0 / 100 |
Hazard Breakdown
| Tornado | Relatively High |
| Hurricane | Very Low |
| Earthquake | Relatively Low |
| Wildfire | Very Low |
| Flood | Relatively Moderate |
| Hail | Relatively Moderate |
| Strong Wind | Relatively High |
| Heat Wave | Relatively Low |
| Winter Weather | Relatively Moderate |
| Lightning | Relatively Moderate |
| Ice Storm | Relatively Low |
| Drought | Relatively Low |
| Cold Wave | Relatively High |
| Landslide | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 21°F (-6°C) | 1.4 in | Coldest |
| February | 24°F (-4°C) | 1.2 in | Driest |
| March | 35°F (2°C) | 2.4 in | |
| April | 47°F (8°C) | 3.7 in | |
| May | 59°F (15°C) | 3.7 in | |
| June | 68°F (20°C) | 4.3 in | Wettest |
| July | 73°F (23°C) | 4.0 in | Warmest |
| August | 70°F (21°C) | 4.2 in | |
| September | 62°F (17°C) | 3.8 in | |
| October | 51°F (10°C) | 2.6 in | |
| November | 37°F (3°C) | 2.7 in | |
| December | 25°F (-4°C) | 2.0 in |
Marengo has a seasonal temperature swing of 52°F / from 21°F in January to 73°F in July. Total annual precipitation is 36.1 inches, with June being the wettest month (4.3") and February the driest (1.2").