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Weather & Climate in Hartly, DE
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Hartly enjoys a temperate climate with an average annual temperature of 57°F (14°C). Winters average 36°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 47.6 inches (wetter than the 38-inch national average). The area receives 13.2 inches of snow annually. Air quality is rated Good with a median AQI of 41. The city sits at an elevation of 70 feet.
Temperature
36°F Jan (2°C)
78°F Jul (26°C)
| Annual Average | 57.1°F |
| 6% above US avg | |
| January Average | 36°F (2°C) |
| July Average | 78°F (26°C) |
| Sunny Days | 293 days/yr |
Geography
| Elevation | 70 ft (21 m) |
| Area | 0.1 sq mi (0.2 km²) |
| Population Density | 2,667/sq mi |
| Coordinates | 39.1683°N, 75.7124°W |
| Timezone | America/New_York |
| County | Kent County County |
| Nearest Airport | Cambridge-Dorchester Regional (CGE) 47 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 41.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively Moderate |
| Risk Score | 84.5 / 100 |
| Social Vulnerability | 32.4 / 100 |
| Community Resilience | 68.2 / 100 |
Hazard Breakdown
| Tornado | Relatively Moderate |
| Hurricane | Relatively Moderate |
| Earthquake | Relatively Low |
| Wildfire | Relatively Low |
| Flood | Relatively Moderate |
| Hail | Relatively Low |
| Strong Wind | Relatively Moderate |
| Heat Wave | Relatively Moderate |
| Winter Weather | Relatively High |
| Lightning | Relatively Moderate |
| Ice Storm | Relatively Moderate |
| Drought | Relatively Moderate |
| Cold Wave | Relatively High |
| Landslide | Very Low |
| Coastal Flood | Relatively Moderate |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
25 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 | 132 km | 5 km |
| Jan 16, 1994 | 0 km E of Sinking Spring, Pennsylvania | M4.2 | 131 km | 5 km |
| Jul 16, 2010 | 5 km NNW of Barnesville, Maryland | M3.6 | 147 km | 7 km |
| Oct 23, 1990 | 3 km W of Hancocks Bridge, New Jersey | M3.2 | 42 km | 10 km |
| Jun 3, 2010 | 4 km ENE of Franklintown, Pennsylvania | M3.1 | 149 km | 2 km |
| Nov 14, 1997 | 0 km S of Rothsville, Pennsylvania | M3.0 | 118 km | 5 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 | 133 km | 5 km |
| May 10, 1993 | 1 km NW of Whitfield, Pennsylvania | M2.8 | 134 km | 5 km |
| Jul 1, 2009 | 3 km ESE of Pennsville, New Jersey | M2.8 | 57 km | 5 km |
| Oct 25, 2009 | 4 km ENE of Franklintown, Pennsylvania | M2.8 | 150 km | 1 km |
| Oct 28, 1994 | 1 km E of Mount Vernon, Maryland | M2.7 | 78 km | — |
| Mar 11, 1995 | 0 km ENE of Landisville, Pennsylvania | M2.7 | 119 km | 5 km |
| Mar 15, 1993 | 5 km W of Columbia, Maryland | M2.7 | 102 km | 5 km |
| Jan 25, 2015 | 4 km ESE of Downingtown, Pennsylvania | M2.6 | 93 km | 2 km |
| Jan 13, 1990 | 6 km ENE of Eldersburg, Maryland | M2.6 | 105 km | 5 km |
| Jun 25, 2021 | 2 km SE of Woodlawn, Maryland | M2.6 | 87 km | 3 km |
| Jan 18, 1994 | 3 km SE of Clay, Pennsylvania | M2.6 | 122 km | 5 km |
| Oct 28, 1996 | 2 km W of Reinholds, Pennsylvania | M2.6 | 128 km | 5 km |
| Jul 5, 1996 | 2 km NW of Chester Heights, Pennsylvania | M2.6 | 84 km | 18 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Hurricane History
8 hurricanes (Category 1+) recorded within 500 km since 1980. Strongest on record: Category 3.
| Year | Name | Category | Max Wind | Closest |
| 2014 | Arthur | Category 1 | 92 mph | 260 km |
| 2012 | Sandy | Category 1 | 92 mph | 238 km |
| 2011 | Irene | Category 1 | 75 mph | 134 km |
| 1999 | Floyd | Category 1 | — | 266 km |
| 1993 | Emily | Category 3 | 115 mph | 290 km |
| 1991 | Bob | Category 3 | 115 mph | 236 km |
| 1986 | Charley | Category 1 | 81 mph | 202 km |
| 1985 | Gloria | Category 2 | 98 mph | 135 km |
Source: NOAA IBTrACS (Category 1+, 1980–2026).
Tornado History
331 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF3. Total: 9 fatalities, 209 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Apr 1, 2023 | EF3 | 46 km | 14.3 mi | 1 |
| Sep 1, 2021 | EF3 | 69 km | 12.4 mi | 0 |
| Apr 28, 2002 | EF3 | 98 km | 18.0 mi | 0 |
| Jul 27, 1994 | EF3 | 63 km | 4.0 mi | 0 |
| Jun 9, 1961 | EF3 | 78 km | 0.1 mi | 0 |
| Apr 28, 1961 | EF3 | 57 km | 0.3 mi | 0 |
| Mar 22, 1955 | EF3 | 90 km | 9.6 mi | 1 |
| Sep 1, 2021 | EF2 | 84 km | 11.4 mi | 0 |
| Sep 1, 2021 | EF2 | 71 km | 5.9 mi | 0 |
| Aug 4, 2020 | EF2 | 80 km | 1.3 mi | 0 |
| Aug 4, 2020 | EF2 | 20 km | 35.8 mi | 0 |
| Oct 31, 2019 | EF2 | 85 km | 0.5 mi | 0 |
| Apr 15, 2019 | EF2 | 67 km | 6.2 mi | 0 |
| Jul 23, 2017 | EF2 | 59 km | 2.4 mi | 0 |
| Feb 24, 2016 | EF2 | 98 km | 4.9 mi | 0 |
| Sep 28, 2004 | EF2 | 58 km | 5.0 mi | 0 |
| Sep 18, 2004 | EF2 | 82 km | 2.0 mi | 0 |
| May 2, 2002 | EF2 | 59 km | 4.5 mi | 0 |
| May 31, 1998 | EF2 | 90 km | 7.0 mi | 0 |
| May 18, 1995 | EF2 | 41 km | 10.0 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 | — | — | 83 km |
Source: NOAA/NCEI Historical Tsunami Database.
Wildfire History
20 wildfires (100+ acres) recorded within 100 km. Largest: BESTPITCH (7,743 acres, 2017).
| Year | Name | Acres Burned | Distance |
| 2017 | BESTPITCH | 7,743 | 90 km |
| 2004 | RETAINING ECOLOGICAL HEALTH | 5,678 | 92 km |
| 2014 | BLACKWATER MARSH WUI BURNS FY14 | 5,433 | 92 km |
| 2005 | MARSH RX-FWS | 4,380 | 89 km |
| 2007 | GUINEA MARSH | 4,173 | 91 km |
| 2009 | DOCTORS CREEK | 3,686 | 91 km |
| 1999 | FB R O C I | 3,525 | 94 km |
| 2019 | MDBWR-FY19-RX-MDWHS SUPPORT | 3,197 | 92 km |
| 2011 | COMPARTMENT J | 2,775 | 92 km |
| 2005 | ISLAND CREEK | 2,729 | 91 km |
| 2004 | UNNAMED | 2,156 | 92 km |
| 1992 | UNNAMED | 2,038 | 89 km |
| 2005 | VEGETATION RESEARCH | 1,926 | 87 km |
| 2011 | THOROFARE | 1,850 | 88 km |
| 1987 | UNNAMED | 1,692 | 91 km |
| 2004 | ROBBINS FIRE | 1,612 | 95 km |
| 1988 | SLAU BCH 2 | 1,578 | 48 km |
| 2020 | SPLIT DITCH | 1,518 | 56 km |
| 2004 | BLACKWATER HAZARD FUEL REDUCTION | 1,518 | 89 km |
| 2020 | BIG TIMBER | 1,434 | 87 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 36°F (2°C) | 3.5 in | |
| February | 35°F (2°C) | 2.9 in | Coldest, Driest |
| March | 43°F (6°C) | 4.1 in | |
| April | 53°F (12°C) | 3.5 in | |
| May | 63°F (17°C) | 4.2 in | |
| June | 71°F (22°C) | 3.8 in | |
| July | 78°F (26°C) | 4.2 in | Warmest, Wettest |
| August | 75°F (24°C) | 4.1 in | |
| September | 68°F (20°C) | 4.1 in | |
| October | 57°F (14°C) | 3.2 in | |
| November | 47°F (8°C) | 3.2 in | |
| December | 38°F (3°C) | 3.5 in |
Hartly has a seasonal temperature swing of 43°F / from 35°F in February to 78°F in July. Total annual precipitation is 44.2 inches, with July being the wettest month (4.2") and February the driest (2.9").