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Weather & Climate in Unionville CDP (Butler County), PA
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Unionville CDP (Butler County) experiences four distinct seasons with an average annual temperature of 49°F (9°C). Winters average 26°F in January while summers reach 70°F in July. The area gets 275 sunny days per year, well above the U.S. average of 205 / making it one of the sunnier locations in the country. Annual precipitation totals 43.2 inches. The area receives 34.9 inches of snow annually, a moderate snowfall amount. Air quality is rated Good with a median AQI of 40. The city sits at an elevation of 1,284 feet.
Temperature
26°F Jan (-3°C)
70°F Jul (21°C)
| Annual Average | 48.5°F |
| 10% below US avg | |
| January Average | 26°F (-3°C) |
| July Average | 70°F (21°C) |
| Sunny Days | 275 days/yr |
Geography
| Elevation | 1,284 ft (391 m) |
| Area | 2.6 sq mi (6.7 km²) |
| Population Density | 279/sq mi |
| Coordinates | 40.9423°N, 79.9613°W |
| Timezone | America/New_York |
| County | Butler County County |
| Nearest Airport | Pittsburgh/Butler Regional (BTP) 11 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 40.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively Low |
| Risk Score | 79.3 / 100 |
| Social Vulnerability | 20.8 / 100 |
| Community Resilience | 86.6 / 100 |
Hazard Breakdown
| Tornado | Relatively Low |
| Hurricane | Very Low |
| Earthquake | Very Low |
| Wildfire | Very Low |
| Flood | Relatively Moderate |
| Hail | Very Low |
| Strong Wind | Relatively Moderate |
| Heat Wave | Relatively Low |
| Winter Weather | Relatively Moderate |
| Lightning | Relatively High |
| Ice Storm | Relatively Low |
| Drought | No Rating |
| Cold Wave | Very Low |
| Landslide | Relatively Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
25 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M4.5.
| Sep 25, 1998 | 2 km SW of Adamsville, Pennsylvania | M4.5 | 71 km | 5 km |
| Jun 10, 2019 | 1 km NW of Timberlake, Ohio | M4.0 | 149 km | 2 km |
| Jan 26, 2001 | 8 km NNW of Edgewood, Ohio | M3.9 | 131 km | 5 km |
| Mar 12, 2007 | Ohio | M3.7 | 125 km | 5 km |
| Aug 28, 2023 | 7 km SE of Madison, Ohio | M3.6 | 122 km | 5 km |
| Jun 30, 2003 | 6 km NW of Perry, Ohio | M3.6 | 141 km | 5 km |
| Oct 16, 1993 | 8 km SSE of Madison, Ohio | M3.6 | 122 km | 5 km |
| Jun 20, 2006 | 9 km WNW of North Perry, Ohio | M3.5 | 146 km | 5 km |
| Jun 3, 2001 | 3 km N of Edgewood, Ohio | M3.4 | 126 km | 5 km |
| Jan 26, 1991 | 1 km NNE of Mayfield Heights, Ohio | M3.4 | 141 km | 5 km |
| Jun 30, 2004 | 2 km WNW of Madison, Ohio | M3.3 | 132 km | 5 km |
| Jul 1, 2013 | 5 km NNW of Fairport Harbor, Ohio | M3.2 | 146 km | 5 km |
| Apr 25, 2010 | 2 km WNW of Madison, Ohio | M3.0 | 132 km | 5 km |
| Mar 30, 2024 | 2 km SSW of Maple Ridge, Ohio | M3.0 | 92 km | 6 km |
| Aug 7, 2000 | 2 km S of Limaville, Ohio | M2.9 | 100 km | 5 km |
| Feb 23, 1995 | 3 km W of Ashtabula, Ohio | M2.9 | 126 km | 5 km |
| May 17, 2010 | 2 km S of Boston Heights, Ohio | M2.7 | 134 km | 5 km |
| Jun 1, 2024 | 1 km E of Madison, Ohio | M2.6 | 128 km | 5 km |
| Jan 5, 2024 | 3 km SE of Madison, Ohio | M2.6 | 126 km | 9 km |
| Feb 14, 2009 | 4 km WSW of Geneva-on-the-Lake, Ohio | M2.6 | 132 km | 5 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
317 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF4. Total: 45 fatalities, 745 injuries.
| Date | Rating | Distance | Path | Fatalities |
| May 31, 1985 | EF4 | 73 km | 29.0 mi | 7 |
| May 31, 1985 | EF4 | 76 km | 56.2 mi | 16 |
| Jun 3, 1980 | EF4 | 38 km | 11.8 mi | 0 |
| May 31, 1985 | EF3 | 45 km | 39.0 mi | 9 |
| May 31, 1985 | EF3 | 88 km | 8.0 mi | 0 |
| May 31, 1985 | EF3 | 91 km | 17.0 mi | 0 |
| May 31, 1985 | EF3 | 86 km | 23.0 mi | 2 |
| Oct 12, 1978 | EF3 | 82 km | 7.3 mi | 0 |
| Jul 11, 1976 | EF3 | 77 km | 11.8 mi | 1 |
| May 2, 1972 | EF3 | 63 km | 7.9 mi | 0 |
| Aug 3, 1963 | EF3 | 70 km | 0.1 mi | 2 |
| Aug 5, 1956 | EF3 | 66 km | 0.1 mi | 2 |
| Mar 1, 1955 | EF3 | 70 km | 2.5 mi | 1 |
| Jun 26, 2024 | EF2 | 66 km | 10.8 mi | 0 |
| May 11, 2024 | EF2 | 75 km | 5.8 mi | 0 |
| May 7, 2024 | EF2 | 81 km | 15.3 mi | 0 |
| Mar 31, 2022 | EF2 | 51 km | 8.6 mi | 0 |
| Oct 21, 2021 | EF2 | 92 km | 15.7 mi | 0 |
| Jul 29, 2021 | EF2 | 94 km | 6.2 mi | 0 |
| Oct 2, 2018 | EF2 | 70 km | 4.1 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Wildfire History
2 wildfires (100+ acres) recorded within 100 km. Largest: UNNAMED (628 acres, 1990).
| Year | Name | Acres Burned | Distance |
| 1990 | UNNAMED | 628 | 77 km |
| 2021 | UNNAMED | 586 | 89 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 26°F (-3°C) | 2.6 in | Coldest |
| February | 28°F (-2°C) | 2.3 in | Driest |
| March | 37°F (3°C) | 3.2 in | |
| April | 48°F (9°C) | 3.3 in | |
| May | 58°F (14°C) | 3.9 in | |
| June | 66°F (19°C) | 4.4 in | Wettest |
| July | 70°F (21°C) | 4.2 in | Warmest |
| August | 69°F (21°C) | 3.8 in | |
| September | 62°F (17°C) | 3.6 in | |
| October | 51°F (10°C) | 2.9 in | |
| November | 41°F (5°C) | 3.3 in | |
| December | 31°F (-1°C) | 3.1 in |
Unionville CDP (Butler County) has a seasonal temperature swing of 44°F / from 26°F in January to 70°F in July. Total annual precipitation is 40.6 inches, with June being the wettest month (4.4") and February the driest (2.3").