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St. Marys, IA
Full City Profile · Iowa · Warren County County
3.3
/5.0
B
Good
112
Population
800/sq mi density
$78,750
Median Income
$45,503 per capita
$168,800
Home Value
$212,840 Zillow
$1,300
Median Rent
23.0% income on rent
50°F
Avg Temperature
275 sunny days/yr
527
Violent Crime/100K
2,312 property/100K
B
Overall
3.3 / 5.0
Good overall score based on economy, affordability, safety and education
A+
Economy
4.5 / 5.0
$78,750 median income, 0.0% unemployment
A+
Affordability
5.0 / 5.0
$168,800 home value, $1,300/mo rent
F
Safety
1.0 / 5.0
527 violent crimes/100K (39% above avg)
C+
Education
2.9 / 5.0
23.2% bachelor's degree or higher
St. Marys experiences four distinct seasons with an average annual temperature of 50°F (10°C). Winters average 22°F in January while summers reach 75°F in July. The area gets 275 sunny days per year. Annual precipitation totals 37.8 inches. The area receives 30.8 inches of snow annually. Air quality is rated Good with a median AQI of 43.
Temperature
22°F Jan (-6°C)
75°F Jul (24°C)
| Annual Average | 49.9°F |
| 8% below US avg | |
| January Average | 22°F (-6°C) |
| July Average | 75°F (24°C) |
| Sunny Days | 275 days/yr |
Geography
| Elevation | 1,036 ft (316 m) |
| Area | 0.1 sq mi (0.4 km²) |
| Population Density | 800/sq mi |
| Coordinates | 41.3077°N, 93.7338°W |
| Timezone | America/Chicago |
| County | Warren County County |
| Nearest Airport | Des Moines International (DSM) 13 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 43.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Very Low |
| Risk Score | 36.1 / 100 |
| Social Vulnerability | 10.6 / 100 |
| Community Resilience | 91.3 / 100 |
Hazard Breakdown
| Tornado | Relatively Moderate |
| Hurricane | Very Low |
| Earthquake | Very Low |
| Wildfire | Very Low |
| Flood | Relatively Low |
| Hail | Relatively Low |
| Strong Wind | Relatively Moderate |
| Heat Wave | Relatively Low |
| Winter Weather | Relatively Low |
| Lightning | Relatively Moderate |
| Ice Storm | Relatively Low |
| Drought | Relatively High |
| Cold Wave | Relatively Low |
| Landslide | Relatively Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 22°F (-6°C) | 0.9 in | Coldest, Driest |
| February | 27°F (-3°C) | 1.0 in | |
| March | 38°F (4°C) | 2.2 in | |
| April | 51°F (10°C) | 3.4 in | |
| May | 61°F (16°C) | 4.3 in | |
| June | 71°F (21°C) | 4.6 in | Wettest |
| July | 75°F (24°C) | 4.2 in | Warmest |
| August | 73°F (23°C) | 3.9 in | |
| September | 65°F (18°C) | 4.0 in | |
| October | 53°F (12°C) | 2.8 in | |
| November | 38°F (3°C) | 2.0 in | |
| December | 26°F (-4°C) | 1.2 in |
St. Marys has a seasonal temperature swing of 53°F / from 22°F in January to 75°F in July. Total annual precipitation is 34.5 inches, with June being the wettest month (4.6") and January the driest (0.9").