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Weather & Climate in Brookside, DE
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Brookside enjoys a temperate climate with an average annual temperature of 56°F (13°C). Winters average 34°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 47.0 inches (wetter than the 38-inch national average). Air quality is rated Good with a median AQI of 41. The city sits at an elevation of 78 feet.
Temperature
34°F Jan (1°C)
78°F Jul (25°C)
| Annual Average | 55.7°F |
| 3% above US avg | |
| January Average | 34°F (1°C) |
| July Average | 78°F (25°C) |
| Sunny Days | 293 days/yr |
Geography
| Elevation | 78 ft (24 m) |
| Area | 4.0 sq mi (10.2 km²) |
| Population Density | 3,934/sq mi |
| Coordinates | 39.6662°N, 75.7066°W |
| Timezone | America/New_York |
| County | New Castle County County |
| Nearest Airport | Philadelphia International (PHL) 29 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 41.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively High |
| Risk Score | 95.3 / 100 |
| Social Vulnerability | 28.5 / 100 |
| Community Resilience | 83.1 / 100 |
Hazard Breakdown
| Tornado | Relatively Moderate |
| Hurricane | Relatively Moderate |
| Earthquake | Relatively Moderate |
| Wildfire | Very Low |
| Flood | Relatively High |
| Hail | Very Low |
| Strong Wind | Relatively High |
| Heat Wave | Relatively Moderate |
| Winter Weather | Very High |
| Lightning | Relatively Moderate |
| Ice Storm | Relatively High |
| Drought | Relatively Moderate |
| Cold Wave | Relatively High |
| Landslide | Relatively Low |
| Coastal Flood | Relatively High |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
33 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M4.8.
| Apr 5, 2024 | 2024 Tewksbury, New Jersey Earthquake | M4.8 | 140 km | 3 km |
| Jan 16, 1994 | 2 km W of Sinking Spring, Pennsylvania | M4.6 | 79 km | 5 km |
| Jan 16, 1994 | 0 km E of Sinking Spring, Pennsylvania | M4.2 | 78 km | 5 km |
| Apr 5, 2024 | 7 km WSW of Gladstone, New Jersey | M3.7 | 140 km | 4 km |
| Oct 23, 1990 | 3 km W of Hancocks Bridge, New Jersey | M3.2 | 24 km | 10 km |
| Aug 26, 2003 | 4 km NNW of Milford, New Jersey | M3.1 | 116 km | 3 km |
| Jan 9, 1992 | 4 km WNW of Robertsville, New Jersey | M3.1 | 140 km | 8 km |
| Jun 3, 2010 | 4 km ENE of Franklintown, Pennsylvania | M3.1 | 118 km | 2 km |
| Nov 14, 1997 | 0 km S of Rothsville, Pennsylvania | M3.0 | 71 km | 5 km |
| Apr 24, 2009 | 1 km S of Franklintown, Pennsylvania | M2.9 | 121 km | 1 km |
| Apr 27, 2024 | 7 km WSW of Gladstone, New Jersey | M2.9 | 140 km | 5 km |
| May 24, 2024 | 6 km E of Califon, New Jersey | M2.9 | 142 km | 7 km |
| Jan 16, 1994 | 0 km SSE of Sinking Spring, Pennsylvania | M2.9 | 77 km | 5 km |
| Sep 15, 2019 | 5 km ESE of East Berlin, Pennsylvania | M2.8 | 107 km | 5 km |
| May 10, 1993 | 1 km NW of Whitfield, Pennsylvania | M2.8 | 80 km | 5 km |
| Jul 1, 2009 | 3 km ESE of Pennsville, New Jersey | M2.8 | 19 km | 5 km |
| Oct 25, 2009 | 4 km ENE of Franklintown, Pennsylvania | M2.8 | 118 km | 1 km |
| Mar 11, 1995 | 0 km ENE of Landisville, Pennsylvania | M2.7 | 76 km | 5 km |
| Oct 28, 1994 | 1 km E of Mount Vernon, Maryland | M2.7 | 87 km | — |
| Mar 15, 1993 | 5 km W of Columbia, Maryland | M2.7 | 113 km | 5 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Hurricane History
6 hurricanes (Category 1+) recorded within 500 km since 1980. Strongest on record: Category 3.
| Year | Name | Category | Max Wind | Closest |
| 2014 | Arthur | Category 1 | 81 mph | 299 km |
| 2012 | Sandy | Category 1 | 92 mph | 265 km |
| 2011 | Irene | Category 1 | 75 mph | 185 km |
| 1991 | Bob | Category 3 | 109 mph | 248 km |
| 1986 | Charley | Category 1 | 75 mph | 256 km |
| 1985 | Gloria | Category 2 | 98 mph | 175 km |
Source: NOAA IBTrACS (Category 1+, 1980–2026).
Tornado History
379 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF3. Total: 13 fatalities, 348 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Sep 1, 2021 | EF3 | 39 km | 12.4 mi | 0 |
| Jul 29, 2021 | EF3 | 79 km | 3.4 mi | 0 |
| May 31, 1998 | EF3 | 92 km | 8.3 mi | 0 |
| Jul 27, 1994 | EF3 | 65 km | 2.0 mi | 3 |
| Jul 27, 1994 | EF3 | 10 km | 4.0 mi | 0 |
| Jun 18, 1970 | EF3 | 96 km | 1.9 mi | 1 |
| Jun 9, 1961 | EF3 | 94 km | 0.1 mi | 0 |
| Apr 28, 1961 | EF3 | 12 km | 0.3 mi | 0 |
| Mar 22, 1955 | EF3 | 35 km | 9.6 mi | 1 |
| Nov 4, 1950 | EF3 | 69 km | 15.9 mi | 0 |
| Sep 1, 2021 | EF2 | 63 km | 8.3 mi | 1 |
| Sep 1, 2021 | EF2 | 25 km | 5.9 mi | 0 |
| Jul 29, 2021 | EF2 | 99 km | 6.3 mi | 0 |
| Aug 4, 2020 | EF2 | 79 km | 20.8 mi | 0 |
| Aug 4, 2020 | EF2 | 65 km | 35.8 mi | 0 |
| Oct 31, 2019 | EF2 | 32 km | 0.5 mi | 0 |
| May 28, 2019 | EF2 | 58 km | 3.1 mi | 0 |
| Jul 23, 2017 | EF2 | 96 km | 2.4 mi | 0 |
| Feb 24, 2016 | EF2 | 47 km | 4.9 mi | 0 |
| Sep 28, 2004 | EF2 | 9 km | 5.0 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Tsunami History
2 tsunamis recorded within 500 km.
| Year | Location | Cause | Max Wave | Deaths | Distance |
| 1895 | HIGH BRIDGE, NJ | Earthquake | — | — | 132 km |
| 1840 | PHILADELPHIA, PENNSYLVANIA | Earthquake | — | — | 46 km |
Source: NOAA/NCEI Historical Tsunami Database.
Wildfire History
20 wildfires (100+ acres) recorded within 100 km. Largest: MULLICA RIVER FIRE (13,082 acres, 2022).
| Year | Name | Acres Burned | Distance |
| 2022 | MULLICA RIVER FIRE | 13,082 | 88 km |
| 2024 | TEA TIME HILL | 4,444 | 96 km |
| 2006 | UNNAMED | 3,780 | 93 km |
| 2017 | PENN SWAMP FIRE | 3,587 | 92 km |
| 2007 | ATSION | 2,705 | 85 km |
| 1996 | UNNAMED | 2,625 | 98 km |
| 1990 | UNNAMED | 2,367 | 80 km |
| 1996 | UNNAMED | 2,122 | 80 km |
| 1997 | UNNAMED | 2,121 | 87 km |
| 1993 | UNNAMED | 1,860 | 80 km |
| 1997 | UNNAMED | 1,833 | 99 km |
| 2008 | SAUNDERS DITCH | 1,814 | 82 km |
| 1985 | UNNAMED | 1,685 | 80 km |
| 1988 | SLAU BCH 2 | 1,578 | 93 km |
| 2020 | SPLIT DITCH | 1,518 | 65 km |
| 2020 | BIG TIMBER | 1,434 | 69 km |
| 2014 | RAILROAD | 1,431 | 65 km |
| 1992 | UNNAMED | 1,416 | 98 km |
| 1991 | UNNAMED | 1,411 | 91 km |
| 1998 | UNNAMED | 1,386 | 88 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 34°F (1°C) | 3.5 in | Coldest |
| February | 34°F (1°C) | 2.8 in | Driest |
| March | 43°F (6°C) | 3.9 in | |
| April | 52°F (11°C) | 3.6 in | |
| May | 62°F (17°C) | 4.3 in | |
| June | 71°F (22°C) | 4.1 in | |
| July | 78°F (25°C) | 4.4 in | Warmest, Wettest |
| August | 75°F (24°C) | 4.0 in | |
| September | 68°F (20°C) | 4.1 in | |
| October | 56°F (13°C) | 3.3 in | |
| November | 47°F (8°C) | 3.4 in | |
| December | 37°F (3°C) | 3.6 in |
Brookside has a seasonal temperature swing of 44°F / from 34°F in January to 78°F in July. Total annual precipitation is 45.0 inches, with July being the wettest month (4.4") and February the driest (2.8").