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Weather & Climate in Arnold, PA
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Arnold experiences four distinct seasons with an average annual temperature of 52°F (11°C). Winters average 29°F in January while summers reach 73°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 42.2 inches. Air quality is rated Good with a median AQI of 40. The city sits at an elevation of 812 feet.
Temperature
29°F Jan (-2°C)
73°F Jul (23°C)
| Annual Average | 51.5°F |
| 5% below US avg | |
| January Average | 29°F (-2°C) |
| July Average | 73°F (23°C) |
| Sunny Days | 275 days/yr |
Geography
| Elevation | 812 ft (247 m) |
| Area | 0.3 sq mi (0.8 km²) |
| Population Density | 6,490/sq mi |
| Coordinates | 40.5789°N, 79.7653°W |
| Timezone | America/New_York |
| County | Allegheny County County |
| Nearest Airport | Pittsburgh/Butler Regional (BTP) 17 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 40.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively High |
| Risk Score | 98.1 / 100 |
| Social Vulnerability | 32.7 / 100 |
| Community Resilience | 91.9 / 100 |
Hazard Breakdown
| Tornado | Relatively High |
| Hurricane | Relatively Low |
| Earthquake | Relatively Low |
| Wildfire | Very Low |
| Flood | Very High |
| Hail | Very Low |
| Strong Wind | Relatively High |
| Heat Wave | Relatively Moderate |
| Winter Weather | Relatively High |
| Lightning | Relatively High |
| Ice Storm | Very High |
| Drought | No Rating |
| Cold Wave | Very High |
| Landslide | Relatively Low |
| Avalanche | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
5 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 | 115 km | 5 km |
| Jun 3, 2017 | 1 km WNW of Batesville, Ohio | M3.4 | 149 km | 2 km |
| Mar 30, 2024 | 2 km SSW of Maple Ridge, Ohio | M3.0 | 115 km | 6 km |
| Aug 7, 2000 | 2 km S of Limaville, Ohio | M2.9 | 124 km | 5 km |
| Sep 11, 2024 | 4 km WNW of Claysville, Pennsylvania | M2.5 | 77 km | 4 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
297 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF4. Total: 15 fatalities, 584 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Jun 2, 1998 | EF4 | 75 km | 36.5 mi | 0 |
| Jun 3, 1980 | EF4 | 8 km | 11.8 mi | 0 |
| May 31, 1985 | EF3 | 65 km | 39.0 mi | 9 |
| Jul 11, 1976 | EF3 | 34 km | 11.8 mi | 1 |
| Aug 3, 1963 | EF3 | 30 km | 0.1 mi | 2 |
| Jun 26, 2024 | EF2 | 22 km | 10.8 mi | 0 |
| May 11, 2024 | EF2 | 43 km | 5.8 mi | 0 |
| May 7, 2024 | EF2 | 88 km | 15.3 mi | 0 |
| Aug 25, 2023 | EF2 | 74 km | 2.0 mi | 0 |
| Aug 1, 2022 | EF2 | 90 km | 1.8 mi | 0 |
| Mar 31, 2022 | EF2 | 43 km | 8.6 mi | 0 |
| Oct 21, 2021 | EF2 | 74 km | 15.7 mi | 0 |
| Oct 2, 2018 | EF2 | 80 km | 4.1 mi | 0 |
| Oct 2, 2018 | EF2 | 58 km | 1.6 mi | 0 |
| Mar 23, 2011 | EF2 | 33 km | 9.0 mi | 0 |
| Nov 10, 2002 | EF2 | 95 km | 7.0 mi | 1 |
| Apr 28, 2002 | EF2 | 45 km | 5.0 mi | 0 |
| Apr 9, 2001 | EF2 | 82 km | 4.0 mi | 0 |
| Jun 2, 1998 | EF2 | 93 km | 15.0 mi | 0 |
| Jun 2, 1998 | EF2 | 93 km | 12.0 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 29°F (-2°C) | 2.5 in | Coldest |
| February | 30°F (-1°C) | 2.4 in | Driest |
| March | 39°F (4°C) | 3.4 in | |
| April | 49°F (9°C) | 3.4 in | |
| May | 59°F (15°C) | 4.0 in | |
| June | 67°F (20°C) | 4.1 in | |
| July | 73°F (23°C) | 4.1 in | Warmest, Wettest |
| August | 70°F (21°C) | 3.7 in | |
| September | 64°F (18°C) | 3.4 in | |
| October | 52°F (11°C) | 2.7 in | |
| November | 42°F (6°C) | 3.2 in | |
| December | 32°F (0°C) | 3.0 in |
Arnold has a seasonal temperature swing of 45°F / from 29°F in January to 73°F in July. Total annual precipitation is 39.8 inches, with July being the wettest month (4.1") and February the driest (2.4").