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Monmouth, IL
Full City Profile · Illinois · Warren County County
3.0
/5.0
B
Good
8,794
Population
2,074/sq mi density
$59,690
Median Income
$29,251 per capita
$88,100
Home Value
$107,948 Zillow
$652
Median Rent
17.9% income on rent
51°F
Avg Temperature
275 sunny days/yr
257
Violent Crime/100K
1,957 property/100K
B
Overall
3.0 / 5.0
Good overall score based on economy, affordability, safety and education
B+
Economy
3.5 / 5.0
$59,690 median income, 4.5% unemployment
A+
Affordability
5.0 / 5.0
$88,100 home value, $652/mo rent
F
Safety
1.0 / 5.0
257 violent crimes/100K
C
Education
2.5 / 5.0
18.7% bachelor's degree or higher
Monmouth experiences four distinct seasons with an average annual temperature of 51°F (11°C). Winters average 23°F in January while summers reach 74°F in July. The area gets 275 sunny days per year. Annual precipitation totals 39.4 inches. The area receives 25.6 inches of snow annually. Air quality is rated Good with a median AQI of 43.
Temperature
23°F Jan (-5°C)
74°F Jul (23°C)
| Annual Average | 50.6°F |
| 6% below US avg | |
| January Average | 23°F (-5°C) |
| July Average | 74°F (23°C) |
| Sunny Days | 275 days/yr |
Geography
| Elevation | 759 ft (231 m) |
| Area | 4.3 sq mi (11.0 km²) |
| Population Density | 2,074/sq mi |
| Coordinates | 40.9142°N, 90.6431°W |
| Timezone | America/Chicago |
| County | Warren County County |
| Nearest Airport | Southeast Iowa Regional (BRL) 27 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 43.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Very Low |
| Risk Score | 15.5 / 100 |
| Social Vulnerability | 22.8 / 100 |
| Community Resilience | 90.6 / 100 |
Hazard Breakdown
| Tornado | Relatively Low |
| Hurricane | Very Low |
| Earthquake | Very Low |
| Wildfire | Very Low |
| Flood | Very Low |
| Hail | Relatively Low |
| Strong Wind | Relatively Low |
| Heat Wave | Relatively Low |
| Winter Weather | Relatively Low |
| Lightning | Relatively Low |
| Ice Storm | Relatively Low |
| Drought | Relatively Moderate |
| Cold Wave | Relatively Low |
| Landslide | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 23°F (-5°C) | 1.5 in | Coldest, Driest |
| February | 27°F (-3°C) | 1.5 in | |
| March | 39°F (4°C) | 2.8 in | |
| April | 51°F (11°C) | 3.8 in | |
| May | 62°F (17°C) | 4.1 in | |
| June | 71°F (22°C) | 4.2 in | |
| July | 74°F (23°C) | 4.4 in | Warmest, Wettest |
| August | 73°F (23°C) | 3.9 in | |
| September | 65°F (18°C) | 3.8 in | |
| October | 53°F (12°C) | 2.9 in | |
| November | 39°F (4°C) | 2.6 in | |
| December | 27°F (-3°C) | 2.2 in |
Monmouth has a seasonal temperature swing of 51°F / from 23°F in January to 74°F in July. Total annual precipitation is 37.6 inches, with July being the wettest month (4.4") and January the driest (1.5").