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Plymouth, IL
Full City Profile · Illinois · McDonough County County
2.7
/5.0
C+
Fair
512
Population
898/sq mi density
$39,750
Median Income
$24,923 per capita
$55,500
Home Value
$104,536 Zillow
$796
Median Rent
36.3% income on rent
52°F
Avg Temperature
275 sunny days/yr
C+
Overall
2.7 / 5.0
Fair overall score based on economy, affordability, safety and education
D
Economy
1.7 / 5.0
$39,750 median income, 11.6% unemployment
A+
Affordability
5.0 / 5.0
$55,500 home value, $796/mo rent
C+
Safety
2.5 / 5.0
0 violent crimes/100K
D
Education
1.7 / 5.0
9.0% bachelor's degree or higher
Plymouth experiences four distinct seasons with an average annual temperature of 52°F (11°C). Winters average 25°F in January while summers reach 75°F in July. The area gets 275 sunny days per year. Annual precipitation totals 40.9 inches. Air quality is rated Good with a median AQI of 43.
Temperature
25°F Jan (-4°C)
75°F Jul (24°C)
| Annual Average | 51.7°F |
| 4% below US avg | |
| January Average | 25°F (-4°C) |
| July Average | 75°F (24°C) |
| Sunny Days | 275 days/yr |
Geography
| Elevation | 644 ft (196 m) |
| Area | 0.2 sq mi (0.6 km²) |
| Population Density | 898/sq mi |
| Coordinates | 40.2921°N, 90.9163°W |
| Timezone | America/Chicago |
| County | McDonough County County |
| Nearest Airport | Quincy Regional-Baldwin Field (UIN) 28 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 43.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Very Low |
| Risk Score | 37.5 / 100 |
| Social Vulnerability | 61.9 / 100 |
| Community Resilience | 74.3 / 100 |
Hazard Breakdown
| Tornado | Relatively Low |
| Hurricane | Very Low |
| Earthquake | Relatively Low |
| Wildfire | Very Low |
| Flood | Very Low |
| Hail | Relatively Moderate |
| Strong Wind | Relatively Moderate |
| Heat Wave | Relatively Moderate |
| Winter Weather | Relatively Low |
| Lightning | Relatively Low |
| Ice Storm | Relatively Moderate |
| Drought | Relatively Moderate |
| Cold Wave | Relatively Moderate |
| Landslide | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 25°F (-4°C) | 1.4 in | Coldest, Driest |
| February | 29°F (-2°C) | 1.5 in | |
| March | 41°F (5°C) | 2.9 in | |
| April | 52°F (11°C) | 3.8 in | |
| May | 63°F (17°C) | 4.4 in | Wettest |
| June | 72°F (22°C) | 3.9 in | |
| July | 75°F (24°C) | 4.3 in | Warmest |
| August | 74°F (23°C) | 3.5 in | |
| September | 66°F (19°C) | 4.1 in | |
| October | 55°F (13°C) | 3.0 in | |
| November | 41°F (5°C) | 2.8 in | |
| December | 29°F (-2°C) | 2.2 in |
Plymouth has a seasonal temperature swing of 50°F / from 25°F in January to 75°F in July. Total annual precipitation is 37.8 inches, with May being the wettest month (4.4") and January the driest (1.4").