Weather & Climate in St. Clair, PA
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
St. Clair experiences four distinct seasons with an average annual temperature of 51°F (11°C). Winters average 28°F in January while summers reach 72°F in July. Annual precipitation totals 40.7 inches. The area receives 25.7 inches of snow annually, a moderate snowfall amount. Air quality is rated Good with a median AQI of 37. 81% of days have good air quality. The city sits at an elevation of 875 feet.
Temperature
28°F Jan (-2°C)
72°F Jul (22°C)
| Annual Average | 51.0°F |
| 6% below US avg | |
| January Average | 28°F (-2°C) |
| July Average | 72°F (22°C) |
Geography
| Elevation | 875 ft (267 m) |
| Area | 0.0 sq mi (0.1 km²) |
| Population Density | 91,833/sq mi |
| Coordinates | 40.4785°N, 78.2284°W |
| Timezone | America/New_York |
| County | Blair County County |
| Nearest Airport | State College Regional (SCE) 37 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 37.0 |
| Rating | Good |
| Good Days % | 80.9% |
| Unhealthy Days | 0 |
Natural Hazard Risk
| Overall Risk | Relatively Low |
| Risk Score | 77.7 / 100 |
| Social Vulnerability | 57.6 / 100 |
| Community Resilience | 94.1 / 100 |
Hazard Breakdown
| Tornado | Relatively Low |
| Hurricane | Relatively Low |
| Earthquake | Relatively Low |
| Wildfire | Very Low |
| Flood | Relatively Moderate |
| Hail | Relatively Low |
| Strong Wind | Relatively Moderate |
| Heat Wave | Relatively Low |
| Winter Weather | Relatively High |
| Lightning | Relatively Moderate |
| Ice Storm | Very Low |
| Drought | No Rating |
| Cold Wave | Relatively Low |
| Landslide | Relatively Low |
| Avalanche | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
6 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M3.4.
| Jun 13, 2019 | 9 km N of Blain, Pennsylvania | M3.4 | 62 km | 27 km |
| Jun 3, 2010 | 4 km ENE of Franklintown, Pennsylvania | M3.1 | 115 km | 2 km |
| Jan 17, 2016 | 3 km NE of Ranson, West Virginia | M3.0 | 133 km | 5 km |
| Apr 24, 2009 | 1 km S of Franklintown, Pennsylvania | M2.9 | 112 km | 1 km |
| Sep 15, 2019 | 5 km ESE of East Berlin, Pennsylvania | M2.8 | 128 km | 5 km |
| Oct 25, 2009 | 4 km ENE of Franklintown, Pennsylvania | M2.8 | 114 km | 1 km |
Source: USGS Earthquake Catalog (M2.5+, 1990-2025). Sorted by magnitude.
Tornado History
175 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF4. Total: 37 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Jun 2, 1998 | EF4 | 97 km | 36.5 mi | 0 |
| May 31, 1985 | EF4 | 86 km | 69.0 mi | 0 |
| Apr 16, 1961 | EF3 | 77 km | 0.1 mi | 0 |
| Apr 19, 2019 | EF2 | 52 km | 4.9 mi | 0 |
| Apr 19, 2019 | EF2 | 72 km | 2.9 mi | 0 |
| May 23, 2011 | EF2 | 90 km | 4.7 mi | 0 |
| Apr 28, 2002 | EF2 | 85 km | 5.0 mi | 0 |
| Aug 15, 1997 | EF2 | 94 km | 3.5 mi | 0 |
| Jul 19, 1996 | EF2 | 45 km | 6.0 mi | 0 |
| Jul 19, 1996 | EF2 | 79 km | 27.4 mi | 0 |
| Sep 26, 1994 | EF2 | 41 km | 3.5 mi | 0 |
| Apr 30, 1994 | EF2 | 90 km | 6.0 mi | 0 |
| Sep 18, 1991 | EF2 | 41 km | 4.0 mi | 0 |
| Nov 20, 1989 | EF2 | 38 km | 3.5 mi | 0 |
| Jun 20, 1989 | EF2 | 63 km | 2.0 mi | 0 |
| Jul 26, 1981 | EF2 | 85 km | 0.1 mi | 0 |
| Jun 9, 1980 | EF2 | 40 km | 7.4 mi | 0 |
| May 12, 1980 | EF2 | 98 km | 2.2 mi | 0 |
| Apr 9, 1980 | EF2 | 82 km | 0.1 mi | 0 |
| Jun 5, 1975 | EF2 | 40 km | 0.1 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950-2024, US only).
Wildfire History
5 wildfires (100+ acres) recorded within 100 km. Largest: BEAR DEN (945 acres, 2014).
| Year | Name | Acres Burned | Distance |
| 2014 | BEAR DEN | 945 | 80 km |
| 2018 | FIELDS RUN | 711 | 80 km |
| 2006 | FIVE MILE FIRE | 658 | 99 km |
| 2006 | BEAR TRAP | 561 | 93 km |
| 2005 | UNNAMED | 510 | 85 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 28°F (-2°C) | 2.7 in | Coldest |
| February | 31°F (-1°C) | 2.3 in | Driest |
| March | 39°F (4°C) | 3.4 in | |
| April | 50°F (10°C) | 3.4 in | |
| May | 60°F (16°C) | 3.9 in | |
| June | 69°F (20°C) | 3.9 in | |
| July | 72°F (22°C) | 3.6 in | Warmest |
| August | 71°F (21°C) | 4.1 in | Wettest |
| September | 64°F (18°C) | 4.0 in | |
| October | 53°F (12°C) | 3.3 in | |
| November | 42°F (6°C) | 3.0 in | |
| December | 33°F (1°C) | 3.1 in |
St. Clair has a seasonal temperature swing of 44°F / from 28°F in January to 72°F in July. Total annual precipitation is 40.7 inches, with August being the wettest month (4.1") and February the driest (2.3").