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Weather & Climate in Delta, PA
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Delta experiences four distinct seasons with an average annual temperature of 55°F (13°C). Winters average 33°F in January while summers reach 78°F in July. The area gets 293 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 48.3 inches (wetter than the 38-inch national average). Air quality is rated Good with a median AQI of 40. The city sits at an elevation of 461 feet.
Temperature
33°F Jan (0°C)
78°F Jul (26°C)
| Annual Average | 55.4°F |
| 3% above US avg | |
| January Average | 33°F (0°C) |
| July Average | 78°F (26°C) |
| Sunny Days | 293 days/yr |
Geography
| Elevation | 461 ft (141 m) |
| Area | 0.1 sq mi (0.3 km²) |
| Population Density | 2,642/sq mi |
| Coordinates | 39.7267°N, 76.3271°W |
| Timezone | America/New_York |
| County | Harford County County |
| Nearest Airport | Harrisburg International (MDT) 40 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 40.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively Low |
| Risk Score | 72.5 / 100 |
| Social Vulnerability | 10.6 / 100 |
| Community Resilience | 91.6 / 100 |
Hazard Breakdown
| Tornado | Relatively Low |
| Hurricane | Relatively Moderate |
| Earthquake | Relatively Low |
| Wildfire | Very Low |
| Flood | Relatively Moderate |
| Hail | Very Low |
| Strong Wind | Relatively Moderate |
| Heat Wave | Relatively Moderate |
| Winter Weather | Relatively High |
| Lightning | Relatively Moderate |
| Ice Storm | Relatively Low |
| Drought | Relatively Moderate |
| Cold Wave | Relatively Moderate |
| Landslide | Very Low |
| Coastal Flood | Relatively Low |
| Avalanche | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
29 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 | 72 km | 5 km |
| Jan 16, 1994 | 0 km E of Sinking Spring, Pennsylvania | M4.2 | 72 km | 5 km |
| Jul 16, 2010 | 5 km NNW of Barnesville, Maryland | M3.6 | 106 km | 7 km |
| Jun 13, 2019 | 9 km N of Blain, Pennsylvania | M3.4 | 127 km | 27 km |
| Oct 23, 1990 | 3 km W of Hancocks Bridge, New Jersey | M3.2 | 74 km | 10 km |
| Aug 26, 2003 | 4 km NNW of Milford, New Jersey | M3.1 | 143 km | 3 km |
| Jun 3, 2010 | 4 km ENE of Franklintown, Pennsylvania | M3.1 | 68 km | 2 km |
| Jan 17, 2016 | 3 km NE of Ranson, West Virginia | M3.0 | 137 km | 5 km |
| Nov 14, 1997 | 0 km S of Rothsville, Pennsylvania | M3.0 | 47 km | 5 km |
| Apr 24, 2009 | 1 km S of Franklintown, Pennsylvania | M2.9 | 71 km | 1 km |
| Jan 16, 1994 | 0 km SSE of Sinking Spring, Pennsylvania | M2.9 | 72 km | 5 km |
| Sep 15, 2019 | 5 km ESE of East Berlin, Pennsylvania | M2.8 | 55 km | 5 km |
| May 10, 1993 | 1 km NW of Whitfield, Pennsylvania | M2.8 | 74 km | 5 km |
| Jul 1, 2009 | 3 km ESE of Pennsville, New Jersey | M2.8 | 73 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 | 42 km | 5 km |
| Oct 28, 1994 | 1 km E of Mount Vernon, Maryland | M2.7 | 53 km | — |
| Mar 15, 1993 | 5 km W of Columbia, Maryland | M2.7 | 74 km | 5 km |
| Jan 25, 2015 | 4 km ESE of Downingtown, Pennsylvania | M2.6 | 65 km | 2 km |
| Jun 25, 2021 | 2 km SE of Woodlawn, Maryland | M2.6 | 57 km | 3 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Hurricane History
3 hurricanes (Category 1+) recorded within 500 km since 1980. Strongest on record: Category 2.
| Year | Name | Category | Max Wind | Closest |
| 2011 | Irene | Category 1 | 75 mph | 214 km |
| 1986 | Charley | Category 1 | 75 mph | 277 km |
| 1985 | Gloria | Category 2 | 98 mph | 216 km |
Source: NOAA IBTrACS (Category 1+, 1980–2026).
Tornado History
447 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF3. Total: 12 fatalities, 311 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Sep 1, 2021 | EF3 | 92 km | 12.4 mi | 0 |
| Jul 14, 2004 | EF3 | 65 km | 7.5 mi | 0 |
| May 31, 1998 | EF3 | 91 km | 8.3 mi | 0 |
| Jul 19, 1996 | EF3 | 61 km | 2.2 mi | 0 |
| Jul 27, 1994 | EF3 | 47 km | 4.0 mi | 0 |
| Jul 27, 1994 | EF3 | 89 km | 2.0 mi | 3 |
| May 22, 1983 | EF3 | 79 km | 2.0 mi | 0 |
| Jun 7, 1980 | EF3 | 63 km | 1.5 mi | 0 |
| Jun 18, 1970 | EF3 | 75 km | 1.9 mi | 1 |
| Jun 9, 1961 | EF3 | 64 km | 0.1 mi | 0 |
| Apr 28, 1961 | EF3 | 65 km | 0.3 mi | 0 |
| Mar 22, 1955 | EF3 | 66 km | 9.6 mi | 1 |
| Apr 5, 1952 | EF3 | 56 km | 17.5 mi | 0 |
| Nov 4, 1950 | EF3 | 56 km | 15.9 mi | 0 |
| Sep 1, 2021 | EF2 | 31 km | 5.9 mi | 0 |
| Aug 4, 2020 | EF2 | 99 km | 35.8 mi | 0 |
| Oct 31, 2019 | EF2 | 72 km | 0.5 mi | 0 |
| May 28, 2019 | EF2 | 60 km | 3.1 mi | 0 |
| Nov 2, 2018 | EF2 | 84 km | 5.5 mi | 0 |
| Jul 23, 2017 | EF2 | 85 km | 2.4 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Tsunami History
1 tsunami recorded within 500 km.
| Year | Location | Cause | Max Wave | Deaths | Distance |
| 1840 | PHILADELPHIA, PENNSYLVANIA | Earthquake | — | — | 97 km |
Source: NOAA/NCEI Historical Tsunami Database.
Wildfire History
4 wildfires (100+ acres) recorded within 100 km. Largest: KENTIS WEST (1,273 acres, 1991).
| Year | Name | Acres Burned | Distance |
| 1991 | KENTIS WEST | 1,273 | 95 km |
| 1988 | BOMBAY ISLAND | 1,020 | 93 km |
| 2012 | HOPEWELL FIRE | 812 | 73 km |
| 1985 | BOMBAY HOOK | 669 | 94 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 33°F (0°C) | 3.2 in | |
| February | 32°F (0°C) | 2.7 in | Coldest, Driest |
| March | 41°F (5°C) | 3.3 in | |
| April | 51°F (11°C) | 3.6 in | |
| May | 61°F (16°C) | 4.1 in | |
| June | 70°F (21°C) | 4.1 in | |
| July | 78°F (26°C) | 4.2 in | Warmest, Wettest |
| August | 74°F (23°C) | 3.9 in | |
| September | 67°F (19°C) | 3.7 in | |
| October | 55°F (13°C) | 3.1 in | |
| November | 46°F (8°C) | 3.6 in | |
| December | 36°F (2°C) | 3.5 in |
Delta has a seasonal temperature swing of 46°F / from 32°F in February to 78°F in July. Total annual precipitation is 42.7 inches, with July being the wettest month (4.2") and February the driest (2.7").