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Weather & Climate in Herndon, PA
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Herndon experiences four distinct seasons with an average annual temperature of 51°F (10°C). Winters average 28°F in January while summers reach 74°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 43.1 inches. The area receives 29.0 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 413 feet.
Temperature
28°F Jan (-3°C)
74°F Jul (23°C)
| Annual Average | 50.8°F |
| 6% below US avg | |
| January Average | 28°F (-3°C) |
| July Average | 74°F (23°C) |
| Sunny Days | 275 days/yr |
Geography
| Elevation | 413 ft (126 m) |
| Area | 0.7 sq mi (1.9 km²) |
| Population Density | 384/sq mi |
| Coordinates | 40.7123°N, 76.8526°W |
| Timezone | America/New_York |
| County | Northumberland County County |
| Nearest Airport | Harrisburg International (MDT) 36 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 40.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively Low |
| Risk Score | 79.2 / 100 |
| Social Vulnerability | 52.8 / 100 |
| Community Resilience | 89.3 / 100 |
Hazard Breakdown
| Tornado | Relatively Low |
| Hurricane | Relatively Low |
| Earthquake | Relatively 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 | Relatively 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
20 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 | 81 km | 5 km |
| Jan 16, 1994 | 0 km E of Sinking Spring, Pennsylvania | M4.2 | 83 km | 5 km |
| Jun 13, 2019 | 9 km N of Blain, Pennsylvania | M3.4 | 64 km | 27 km |
| Aug 26, 2003 | 4 km NNW of Milford, New Jersey | M3.1 | 148 km | 3 km |
| Jun 3, 2010 | 4 km ENE of Franklintown, Pennsylvania | M3.1 | 70 km | 2 km |
| Nov 14, 1997 | 0 km S of Rothsville, Pennsylvania | M3.0 | 81 km | 5 km |
| Apr 24, 2009 | 1 km S of Franklintown, Pennsylvania | M2.9 | 74 km | 1 km |
| Jan 16, 1994 | 0 km SSE of Sinking Spring, Pennsylvania | M2.9 | 84 km | 5 km |
| Sep 15, 2019 | 5 km ESE of East Berlin, Pennsylvania | M2.8 | 88 km | 5 km |
| Jun 10, 2025 | 10 km NW of Forksville, Pennsylvania | M2.8 | 96 km | 8 km |
| May 10, 1993 | 1 km NW of Whitfield, Pennsylvania | M2.8 | 81 km | 5 km |
| Oct 25, 2009 | 4 km ENE of Franklintown, Pennsylvania | M2.8 | 69 km | 1 km |
| Mar 11, 1995 | 0 km ENE of Landisville, Pennsylvania | M2.7 | 78 km | 5 km |
| Jan 25, 2015 | 4 km ESE of Downingtown, Pennsylvania | M2.6 | 129 km | 2 km |
| Jan 18, 1994 | 3 km SE of Clay, Pennsylvania | M2.6 | 78 km | 5 km |
| Oct 28, 1996 | 2 km W of Reinholds, Pennsylvania | M2.6 | 78 km | 5 km |
| Jan 13, 1990 | 6 km ENE of Eldersburg, Maryland | M2.6 | 143 km | 5 km |
| Jul 5, 1996 | 2 km NW of Chester Heights, Pennsylvania | M2.6 | 146 km | 18 km |
| May 7, 1994 | 2 km SW of Sinking Spring, Pennsylvania | M2.5 | 82 km | 5 km |
| Jan 8, 1995 | 1 km WSW of Montrose Manor, Pennsylvania | M2.5 | 85 km | 5 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Hurricane History
1 hurricane (Category 1+) recorded within 500 km since 1980. Strongest on record: Category 1.
| Year | Name | Category | Max Wind | Closest |
| 1985 | Gloria | Category 2 | 98 mph | 287 km |
Source: NOAA IBTrACS (Category 1+, 1980–2026).
Tornado History
290 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF3. Total: 9 fatalities, 169 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Jul 14, 2004 | EF3 | 53 km | 7.5 mi | 0 |
| May 31, 1998 | EF3 | 85 km | 8.3 mi | 0 |
| May 31, 1985 | EF3 | 58 km | 19.0 mi | 6 |
| Jun 7, 1980 | EF3 | 88 km | 1.5 mi | 0 |
| Jul 29, 1976 | EF3 | 65 km | 25.0 mi | 0 |
| Jun 18, 1970 | EF3 | 58 km | 1.9 mi | 1 |
| Apr 16, 1961 | EF3 | 93 km | 0.1 mi | 0 |
| Nov 4, 1950 | EF3 | 84 km | 15.9 mi | 0 |
| Apr 19, 2019 | EF2 | 67 km | 4.9 mi | 0 |
| Apr 14, 2019 | EF2 | 65 km | 3.7 mi | 0 |
| Oct 2, 2018 | EF2 | 97 km | 2.2 mi | 0 |
| Jul 8, 2014 | EF2 | 98 km | 6.7 mi | 0 |
| May 23, 2011 | EF2 | 29 km | 4.7 mi | 0 |
| Apr 28, 2011 | EF2 | 42 km | 1.1 mi | 0 |
| Apr 28, 2011 | EF2 | 68 km | 2.6 mi | 0 |
| Dec 1, 2006 | EF2 | 77 km | 20.0 mi | 0 |
| May 29, 1995 | EF2 | 87 km | 2.5 mi | 0 |
| Oct 9, 1992 | EF2 | 66 km | 2.0 mi | 0 |
| Jul 17, 1992 | EF2 | 53 km | 1.0 mi | 0 |
| Jul 15, 1992 | EF2 | 74 km | 1.5 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Wildfire History
4 wildfires (100+ acres) recorded within 100 km. Largest: PENOBSCOT (2,091 acres, 2009).
| Year | Name | Acres Burned | Distance |
| 2009 | PENOBSCOT | 2,091 | 99 km |
| 2004 | CRYSTAL LAKE | 1,838 | 99 km |
| 2015 | RAZOR FIRE | 728 | 99 km |
| 2006 | OKOME ROAD | 573 | 88 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 28°F (-3°C) | 2.8 in | Coldest |
| February | 29°F (-2°C) | 2.6 in | Driest |
| March | 38°F (3°C) | 3.2 in | |
| April | 49°F (9°C) | 3.5 in | |
| May | 59°F (15°C) | 4.1 in | |
| June | 68°F (20°C) | 4.4 in | Wettest |
| July | 74°F (23°C) | 3.9 in | Warmest |
| August | 71°F (22°C) | 3.6 in | |
| September | 64°F (18°C) | 3.9 in | |
| October | 52°F (11°C) | 3.3 in | |
| November | 42°F (6°C) | 3.6 in | |
| December | 32°F (0°C) | 3.1 in |
Herndon has a seasonal temperature swing of 46°F / from 28°F in January to 74°F in July. Total annual precipitation is 42.0 inches, with June being the wettest month (4.4") and February the driest (2.6").