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Weather & Climate in Adelphi, MD
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Adelphi enjoys a temperate climate with an average annual temperature of 58°F (15°C). Winters average 36°F in January while summers reach 80°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 45.6 inches. The area receives 9.7 inches of snow annually. Air quality is rated Good with a median AQI of 41. The city sits at an elevation of 113 feet.
Temperature
36°F Jan (2°C)
80°F Jul (27°C)
| Annual Average | 58.3°F |
| 8% above US avg | |
| January Average | 36°F (2°C) |
| July Average | 80°F (27°C) |
| Sunny Days | 293 days/yr |
Geography
| Elevation | 113 ft (34 m) |
| Area | 2.7 sq mi (7.0 km²) |
| Population Density | 6,327/sq mi |
| Coordinates | 38.9971°N, 76.9668°W |
| Timezone | America/New_York |
| County | Prince George's County County |
| Nearest Airport | Ronald Reagan Washington Ntl (DCA) 11 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 41.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively Moderate |
| Risk Score | 93.2 / 100 |
| Social Vulnerability | 49.4 / 100 |
| Community Resilience | 29.8 / 100 |
Hazard Breakdown
| Tornado | Relatively High |
| Hurricane | Relatively Moderate |
| Earthquake | Relatively Moderate |
| Wildfire | Very Low |
| Flood | Relatively High |
| Hail | Relatively Moderate |
| Strong Wind | Relatively High |
| Heat Wave | Relatively High |
| Winter Weather | Very High |
| Lightning | Very High |
| Ice Storm | Relatively Moderate |
| Drought | Relatively Moderate |
| Cold Wave | Relatively Moderate |
| Landslide | Relatively Moderate |
| Coastal Flood | Relatively Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
38 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M5.8.
| Aug 23, 2011 | 11 km SSW of Mineral, Virginia | M5.8 | 148 km | 6 km |
| Aug 25, 2011 | 8 km SW of Mineral, Virginia | M4.5 | 146 km | 7 km |
| Aug 24, 2011 | 11 km SSW of Mineral, Virginia | M4.2 | 148 km | 0 km |
| Jul 16, 2010 | 5 km NNW of Barnesville, Maryland | M3.6 | 48 km | 7 km |
| Sep 1, 2011 | 7 km SSW of Mineral, Virginia | M3.4 | 144 km | 3 km |
| Oct 23, 1990 | 3 km W of Hancocks Bridge, New Jersey | M3.2 | 138 km | 10 km |
| Jan 30, 2012 | 9 km SSE of Louisa, Virginia | M3.1 | 147 km | 3 km |
| Jun 3, 2010 | 4 km ENE of Franklintown, Pennsylvania | M3.1 | 121 km | 2 km |
| Jan 17, 2016 | 3 km NE of Ranson, West Virginia | M3.0 | 83 km | 5 km |
| Oct 2, 2010 | 10 km NNW of Ashland, Virginia | M3.0 | 136 km | 19 km |
| Nov 14, 1997 | 0 km S of Rothsville, Pennsylvania | M3.0 | 142 km | 5 km |
| Oct 12, 2011 | 9 km S of Louisa, Virginia | M3.0 | 147 km | 4 km |
| Apr 24, 2009 | 1 km S of Franklintown, Pennsylvania | M2.9 | 119 km | 1 km |
| Sep 15, 2019 | 5 km ESE of East Berlin, Pennsylvania | M2.8 | 103 km | 5 km |
| Mar 15, 2015 | 6 km SW of Mineral, Virginia | M2.8 | 144 km | 5 km |
| Aug 23, 2011 | 9 km SSW of Mineral, Virginia | M2.8 | 146 km | 0 km |
| Jul 1, 2009 | 3 km ESE of Pennsville, New Jersey | M2.8 | 147 km | 5 km |
| Oct 25, 2009 | 4 km ENE of Franklintown, Pennsylvania | M2.8 | 122 km | 1 km |
| Mar 15, 1993 | 5 km W of Columbia, Maryland | M2.7 | 27 km | 5 km |
| Feb 19, 2012 | 12 km S of Louisa, Virginia | M2.7 | 150 km | 3 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Hurricane History
5 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 | 198 km |
| 2003 | Isabel | Category 1 | 75 mph | 263 km |
| 1999 | Floyd | Category 1 | — | 256 km |
| 1986 | Charley | Category 1 | 81 mph | 235 km |
| 1985 | Gloria | Category 2 | 98 mph | 224 km |
Source: NOAA IBTrACS (Category 1+, 1980–2026).
Tornado History
487 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF4. Total: 9 fatalities, 363 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Apr 28, 2002 | EF4 | 53 km | 38.0 mi | 3 |
| Sep 24, 2001 | EF4 | 100 km | 10.0 mi | 0 |
| Sep 17, 2004 | EF3 | 90 km | 9.0 mi | 0 |
| Apr 28, 2002 | EF3 | 86 km | 18.0 mi | 0 |
| Sep 24, 2001 | EF3 | 8 km | 17.5 mi | 2 |
| Jul 19, 1996 | EF3 | 56 km | 2.2 mi | 0 |
| May 22, 1983 | EF3 | 82 km | 2.0 mi | 0 |
| Sep 5, 1979 | EF3 | 26 km | 17.9 mi | 1 |
| Jan 26, 1978 | EF3 | 62 km | 0.7 mi | 1 |
| Apr 1, 1973 | EF3 | 38 km | 9.8 mi | 0 |
| Jun 9, 1961 | EF3 | 38 km | 0.1 mi | 0 |
| Apr 5, 1952 | EF3 | 89 km | 17.5 mi | 0 |
| Sep 1, 2021 | EF2 | 36 km | 11.4 mi | 0 |
| Nov 2, 2018 | EF2 | 43 km | 5.5 mi | 0 |
| Jul 23, 2017 | EF2 | 54 km | 2.4 mi | 0 |
| May 8, 2008 | EF2 | 86 km | 3.4 mi | 0 |
| Sep 18, 2004 | EF2 | 94 km | 2.0 mi | 0 |
| Sep 17, 2004 | EF2 | 75 km | 13.0 mi | 0 |
| Sep 17, 2004 | EF2 | 43 km | 15.0 mi | 0 |
| Sep 17, 2004 | EF2 | 57 km | 4.0 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Wildfire History
4 wildfires (100+ acres) recorded within 100 km. Largest: BLACKWATER HAZARD FUEL REDUCTION (1,518 acres, 2004).
| Year | Name | Acres Burned | Distance |
| 2004 | BLACKWATER HAZARD FUEL REDUCTION | 1,518 | 96 km |
| 1999 | NCO | 816 | 61 km |
| 2001 | A 1 M 2 | 594 | 96 km |
| 2005 | A 1 | 561 | 96 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 36°F (2°C) | 3.2 in | Coldest |
| February | 37°F (3°C) | 2.8 in | Driest |
| March | 45°F (7°C) | 3.7 in | |
| April | 55°F (13°C) | 3.3 in | |
| May | 65°F (18°C) | 4.4 in | Wettest |
| June | 73°F (23°C) | 3.6 in | |
| July | 80°F (27°C) | 4.2 in | Warmest |
| August | 76°F (25°C) | 3.9 in | |
| September | 70°F (21°C) | 3.9 in | |
| October | 58°F (14°C) | 3.4 in | |
| November | 48°F (9°C) | 3.4 in | |
| December | 39°F (4°C) | 3.3 in |
Adelphi has a seasonal temperature swing of 44°F / from 36°F in January to 80°F in July. Total annual precipitation is 43.1 inches, with May being the wettest month (4.4") and February the driest (2.8").