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Weather & Climate in Sumner, IA
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Sumner experiences four distinct seasons with an average annual temperature of 46°F (8°C). Winters average 16°F in January while summers reach 72°F in July. The area gets 260 sunny days per year, above the national average. Annual precipitation totals 38.6 inches. Air quality is rated Good with a median AQI of 43. The city sits at an elevation of 1,061 feet.
Temperature
16°F Jan (-9°C)
72°F Jul (22°C)
| Annual Average | 46.4°F |
| 14% below US avg | |
| January Average | 16°F (-9°C) |
| July Average | 72°F (22°C) |
| Sunny Days | 260 days/yr |
Geography
| Elevation | 1,061 ft (323 m) |
| Area | 2.5 sq mi (6.4 km²) |
| Population Density | 878/sq mi |
| Coordinates | 42.8494°N, 92.0972°W |
| Timezone | America/Chicago |
| County | Bremer County County |
| Nearest Airport | Waterloo Regional (ALO) 25 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 43.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Very Low |
| Risk Score | 24.6 / 100 |
| Social Vulnerability | 10.6 / 100 |
| Community Resilience | 98.0 / 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 | Very Low |
| Winter Weather | Relatively Low |
| Lightning | Very Low |
| Ice Storm | Very Low |
| Drought | Relatively Moderate |
| Cold Wave | Relatively Low |
| Landslide | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Tornado History
550 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF5. Total: 35 fatalities, 929 injuries.
| Date | Rating | Distance | Path | Fatalities |
| May 25, 2008 | EF5 | 72 km | 41.0 mi | 9 |
| May 15, 1968 | EF5 | 84 km | 62.1 mi | 13 |
| May 15, 1968 | EF5 | 24 km | 13.1 mi | 5 |
| Mar 13, 1990 | EF4 | 88 km | 19.0 mi | 0 |
| Aug 12, 1974 | EF4 | 75 km | 5.0 mi | 0 |
| Jul 12, 1971 | EF4 | 51 km | 10.9 mi | 0 |
| Aug 26, 1965 | EF4 | 62 km | 4.7 mi | 1 |
| May 5, 1965 | EF4 | 76 km | 41.6 mi | 0 |
| Sep 1, 1961 | EF4 | 74 km | 26.6 mi | 0 |
| Apr 30, 1954 | EF4 | 88 km | 80.4 mi | 0 |
| May 10, 1953 | EF4 | 71 km | 162.0 mi | 2 |
| May 25, 2008 | EF3 | 28 km | 32.0 mi | 0 |
| Jun 11, 2004 | EF3 | 71 km | 12.0 mi | 0 |
| May 21, 2004 | EF3 | 92 km | 3.0 mi | 0 |
| May 11, 2000 | EF3 | 47 km | 18.6 mi | 1 |
| Jul 27, 1995 | EF3 | 44 km | 20.0 mi | 0 |
| Jul 19, 1994 | EF3 | 52 km | 23.0 mi | 0 |
| Jun 19, 1993 | EF3 | 67 km | 9.0 mi | 0 |
| Jun 28, 1990 | EF3 | 91 km | 9.0 mi | 0 |
| May 30, 1985 | EF3 | 46 km | 34.0 mi | 2 |
Source: NOAA Storm Prediction Center (EF0+, 1950-2024, US only).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 16°F (-9°C) | 1.0 in | Coldest, Driest |
| February | 21°F (-6°C) | 1.0 in | |
| March | 33°F (1°C) | 2.2 in | |
| April | 47°F (8°C) | 3.6 in | |
| May | 59°F (15°C) | 4.3 in | |
| June | 68°F (20°C) | 4.5 in | |
| July | 72°F (22°C) | 4.5 in | Warmest |
| August | 69°F (21°C) | 4.7 in | Wettest |
| September | 61°F (16°C) | 3.6 in | |
| October | 50°F (10°C) | 2.6 in | |
| November | 34°F (1°C) | 2.2 in | |
| December | 20°F (-7°C) | 1.4 in |
Sumner has a seasonal temperature swing of 56°F / from 16°F in January to 72°F in July. Total annual precipitation is 35.6 inches, with August being the wettest month (4.7") and January the driest (1.0").