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Round Lake, IL
Full City Profile · Illinois · McHenry County County
3.7
/5.0
B+
Good
18,588
Population
3,343/sq mi density
$108,965
Median Income
$42,300 per capita
$257,400
Home Value
$317,780 Zillow
$1,494
Median Rent
33.1% income on rent
48°F
Avg Temperature
260 sunny days/yr
88
Violent Crime/100K
657 property/100K
B+
Overall
3.7 / 5.0
Good overall score based on economy, affordability, safety and education
A+
Economy
4.5 / 5.0
$108,965 median income, 4.8% unemployment
A+
Affordability
5.0 / 5.0
$257,400 home value, $1,494/mo rent
F
Safety
1.0 / 5.0
88 violent crimes/100K
A
Education
4.2 / 5.0
40.5% bachelor's degree or higher
Round Lake experiences four distinct seasons with an average annual temperature of 48°F (9°C). Winters average 21°F in January while summers reach 72°F in July. The area gets 260 sunny days per year. Annual precipitation totals 38.5 inches. The area receives 43.1 inches of snow annually. Air quality is rated Good with a median AQI of 43.
Temperature
21°F Jan (-6°C)
72°F Jul (22°C)
| Annual Average | 47.9°F |
| 11% below US avg | |
| January Average | 21°F (-6°C) |
| July Average | 72°F (22°C) |
| Sunny Days | 260 days/yr |
Geography
| Elevation | 767 ft (234 m) |
| Area | 5.6 sq mi (14.4 km²) |
| Population Density | 3,343/sq mi |
| Coordinates | 42.3432°N, 88.1021°W |
| Timezone | America/Chicago |
| County | McHenry County County |
| Nearest Airport | Kenosha Regional (ENW) 20 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)
Tsunami History
1 tsunami recorded within 500 km. Highest wave on record: 3.0 m (10 ft).
| Year | Location | Cause | Max Wave | Deaths | Distance |
| 1954 | MICHIGAN CITY, IN (LAKE MICHIGAN) | Avalanche | 3.0 m | 7 | 124 km |
Source: NOAA/NCEI Historical Tsunami Database. Sorted by wave height.
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 21°F (-6°C) | 1.6 in | Coldest |
| February | 24°F (-4°C) | 1.3 in | Driest |
| March | 35°F (1°C) | 2.5 in | |
| April | 46°F (8°C) | 3.6 in | |
| May | 57°F (14°C) | 3.4 in | |
| June | 67°F (19°C) | 3.8 in | |
| July | 72°F (22°C) | 4.0 in | Warmest |
| August | 70°F (21°C) | 4.1 in | Wettest |
| September | 62°F (17°C) | 3.8 in | |
| October | 51°F (11°C) | 2.4 in | |
| November | 38°F (3°C) | 2.6 in | |
| December | 26°F (-4°C) | 2.1 in |
Round Lake has a seasonal temperature swing of 51°F / from 21°F in January to 72°F in July. Total annual precipitation is 35.2 inches, with August being the wettest month (4.1") and February the driest (1.3").