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Weather & Climate in South Williamsport, PA
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
South Williamsport experiences four distinct seasons with an average annual temperature of 50°F (10°C). Winters average 27°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 41.7 inches. The area receives 29.6 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 530 feet.
Temperature
27°F Jan (-3°C)
73°F Jul (23°C)
| Annual Average | 50.3°F |
| 7% below US avg | |
| January Average | 27°F (-3°C) |
| July Average | 73°F (23°C) |
| Sunny Days | 275 days/yr |
Geography
| Elevation | 530 ft (162 m) |
| Area | 2.2 sq mi (5.6 km²) |
| Population Density | 3,272/sq mi |
| Coordinates | 41.2294°N, 77.0005°W |
| Timezone | America/New_York |
| County | Lycoming County County |
| Nearest Airport | Williamsport Regional (IPT) 4 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 40.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively Low |
| Risk Score | 79.6 / 100 |
| Social Vulnerability | 41.9 / 100 |
| Community Resilience | 88.6 / 100 |
Hazard Breakdown
| Tornado | Relatively Low |
| Hurricane | Relatively Low |
| Earthquake | Very Low |
| Wildfire | Very Low |
| Flood | Relatively Moderate |
| Hail | Very Low |
| Strong Wind | Relatively High |
| 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 | Relatively Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
17 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M4.6.
| Jan 16, 1994 | 2 km W of Sinking Spring, Pennsylvania | M4.6 | 129 km | 5 km |
| Jan 16, 1994 | 0 km E of Sinking Spring, Pennsylvania | M4.2 | 131 km | 5 km |
| Jun 13, 2019 | 9 km N of Blain, Pennsylvania | M3.4 | 99 km | 27 km |
| Feb 3, 2001 | 6 km W of Bath, New York | M3.2 | 128 km | 0 km |
| Jun 3, 2010 | 4 km ENE of Franklintown, Pennsylvania | M3.1 | 127 km | 2 km |
| Nov 14, 1997 | 0 km S of Rothsville, Pennsylvania | M3.0 | 136 km | 5 km |
| Apr 24, 2009 | 1 km S of Franklintown, Pennsylvania | M2.9 | 130 km | 1 km |
| Jan 16, 1994 | 0 km SSE of Sinking Spring, Pennsylvania | M2.9 | 131 km | 5 km |
| Sep 15, 2019 | 5 km ESE of East Berlin, Pennsylvania | M2.8 | 145 km | 5 km |
| Jun 10, 2025 | 10 km NW of Forksville, Pennsylvania | M2.8 | 46 km | 8 km |
| May 10, 1993 | 1 km NW of Whitfield, Pennsylvania | M2.8 | 128 km | 5 km |
| Oct 25, 2009 | 4 km ENE of Franklintown, Pennsylvania | M2.8 | 126 km | 1 km |
| Mar 11, 1995 | 0 km ENE of Landisville, Pennsylvania | M2.7 | 135 km | 5 km |
| Jan 18, 1994 | 3 km SE of Clay, Pennsylvania | M2.6 | 132 km | 5 km |
| Oct 28, 1996 | 2 km W of Reinholds, Pennsylvania | M2.6 | 129 km | 5 km |
| May 7, 1994 | 2 km SW of Sinking Spring, Pennsylvania | M2.5 | 130 km | 5 km |
| Jan 8, 1995 | 1 km WSW of Montrose Manor, Pennsylvania | M2.5 | 133 km | 5 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
209 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF3. Total: 10 fatalities, 129 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Jun 2, 1998 | EF3 | 90 km | 26.0 mi | 2 |
| May 31, 1985 | EF3 | 14 km | 19.0 mi | 6 |
| May 2, 1983 | EF3 | 93 km | 15.0 mi | 0 |
| May 2, 1983 | EF3 | 94 km | 2.0 mi | 0 |
| Jul 29, 1976 | EF3 | 23 km | 25.0 mi | 0 |
| Apr 19, 2019 | EF2 | 93 km | 4.9 mi | 0 |
| Apr 14, 2019 | EF2 | 50 km | 3.7 mi | 0 |
| Oct 2, 2018 | EF2 | 38 km | 2.2 mi | 0 |
| Jun 13, 2018 | EF2 | 60 km | 5.2 mi | 0 |
| Jun 13, 2018 | EF2 | 97 km | 2.9 mi | 0 |
| Jul 8, 2014 | EF2 | 56 km | 6.7 mi | 0 |
| May 23, 2011 | EF2 | 66 km | 4.7 mi | 0 |
| Apr 28, 2011 | EF2 | 99 km | 1.1 mi | 0 |
| Dec 1, 2006 | EF2 | 79 km | 20.0 mi | 0 |
| Jul 15, 1992 | EF2 | 92 km | 1.5 mi | 0 |
| Sep 18, 1991 | EF2 | 93 km | 4.0 mi | 0 |
| Nov 20, 1989 | EF2 | 97 km | 3.5 mi | 0 |
| Aug 28, 1988 | EF2 | 86 km | 1.5 mi | 0 |
| Jul 6, 1984 | EF2 | 71 km | 0.3 mi | 0 |
| May 2, 1983 | EF2 | 86 km | 9.8 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Wildfire History
8 wildfires (100+ acres) recorded within 100 km. Largest: PENOBSCOT (2,091 acres, 2009).
| Year | Name | Acres Burned | Distance |
| 2009 | PENOBSCOT | 2,091 | 96 km |
| 2008 | BULL RUN | 2,003 | 53 km |
| 2004 | CRYSTAL LAKE | 1,838 | 98 km |
| 2009 | WOODRUFF | 757 | 73 km |
| 2018 | FIELDS RUN | 711 | 78 km |
| 2006 | FIVE MILE FIRE | 658 | 75 km |
| 2006 | OKOME ROAD | 573 | 37 km |
| 2006 | BEAR TRAP | 561 | 69 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 27°F (-3°C) | 2.4 in | Coldest, Driest |
| February | 28°F (-2°C) | 2.5 in | |
| March | 36°F (2°C) | 3.0 in | |
| April | 48°F (9°C) | 3.2 in | |
| May | 58°F (15°C) | 3.8 in | |
| June | 67°F (19°C) | 4.4 in | Wettest |
| July | 73°F (23°C) | 4.1 in | Warmest |
| August | 70°F (21°C) | 3.4 in | |
| September | 62°F (17°C) | 3.7 in | |
| October | 51°F (10°C) | 3.2 in | |
| November | 40°F (5°C) | 3.5 in | |
| December | 30°F (-1°C) | 2.8 in |
South Williamsport has a seasonal temperature swing of 46°F / from 27°F in January to 73°F in July. Total annual precipitation is 40.0 inches, with June being the wettest month (4.4") and January the driest (2.4").