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Weather & Climate in Green Valley, MD
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Green Valley experiences four distinct seasons with an average annual temperature of 54°F (12°C). Winters average 32°F in January while summers reach 75°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 47.9 inches (wetter than the 38-inch national average). The area receives 31.4 inches of snow annually, a moderate snowfall amount. Air quality is rated Good with a median AQI of 41. The city sits at an elevation of 663 feet.
Temperature
32°F Jan (-0°C)
75°F Jul (24°C)
| Annual Average | 54.0°F |
| 0% below US avg | |
| January Average | 32°F (-0°C) |
| July Average | 75°F (24°C) |
| Sunny Days | 293 days/yr |
Geography
| Elevation | 663 ft (202 m) |
| Area | 17.1 sq mi (44.3 km²) |
| Population Density | 771/sq mi |
| Coordinates | 39.3418°N, 77.2403°W |
| Timezone | America/New_York |
| County | Frederick County County |
| Nearest Airport | Baltimore/Washington International Thurgood Marshall (BWI) 33 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 41.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively Low |
| Risk Score | 74.2 / 100 |
| Social Vulnerability | 10.6 / 100 |
| Community Resilience | 77.8 / 100 |
Hazard Breakdown
| Tornado | Relatively Moderate |
| Hurricane | Relatively Low |
| Earthquake | Relatively Low |
| Wildfire | Very Low |
| Flood | Relatively Moderate |
| Hail | Relatively Moderate |
| Strong Wind | Relatively Moderate |
| Heat Wave | Relatively Moderate |
| Winter Weather | Relatively High |
| Lightning | Relatively High |
| Ice Storm | Relatively Low |
| Drought | Relatively Moderate |
| 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: M3.6.
| Jul 16, 2010 | 5 km NNW of Barnesville, Maryland | M3.6 | 17 km | 7 km |
| Jun 13, 2019 | 9 km N of Blain, Pennsylvania | M3.4 | 122 km | 27 km |
| Jun 3, 2010 | 4 km ENE of Franklintown, Pennsylvania | M3.1 | 86 km | 2 km |
| Jan 17, 2016 | 3 km NE of Ranson, West Virginia | M3.0 | 51 km | 5 km |
| Nov 14, 1997 | 0 km S of Rothsville, Pennsylvania | M3.0 | 123 km | 5 km |
| Apr 24, 2009 | 1 km S of Franklintown, Pennsylvania | M2.9 | 82 km | 1 km |
| Sep 15, 2019 | 5 km ESE of East Berlin, Pennsylvania | M2.8 | 71 km | 5 km |
| Oct 25, 2009 | 4 km ENE of Franklintown, Pennsylvania | M2.8 | 87 km | 1 km |
| Mar 15, 1993 | 5 km W of Columbia, Maryland | M2.7 | 32 km | 5 km |
| Mar 11, 1995 | 0 km ENE of Landisville, Pennsylvania | M2.7 | 111 km | 5 km |
| Oct 28, 1994 | 1 km E of Mount Vernon, Maryland | M2.7 | 55 km | — |
| Jan 13, 1990 | 6 km ENE of Eldersburg, Maryland | M2.6 | 32 km | 5 km |
| Jun 25, 2021 | 2 km SE of Woodlawn, Maryland | M2.6 | 46 km | 3 km |
| Jan 18, 1994 | 3 km SE of Clay, Pennsylvania | M2.6 | 129 km | 5 km |
| Oct 28, 1996 | 2 km W of Reinholds, Pennsylvania | M2.6 | 139 km | 5 km |
| Mar 10, 1993 | 3 km WSW of Columbia, Maryland | M2.5 | 33 km | 5 km |
| Jul 27, 1997 | 5 km SSE of Culpeper, Virginia | M2.5 | 120 km | 19 km |
| Sep 29, 1997 | Virginia | M2.5 | 61 km | 3 km |
| Jun 25, 2001 | 8 km S of Remington, Virginia | M2.5 | 110 km | 5 km |
| May 7, 1994 | 2 km SW of Sinking Spring, Pennsylvania | M2.5 | 149 km | 5 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 | 238 km |
| 2003 | Isabel | Category 1 | 75 mph | 297 km |
| 1999 | Floyd | Category 1 | — | 300 km |
| 1986 | Charley | Category 1 | 75 mph | 280 km |
| 1985 | Gloria | Category 2 | 98 mph | 259 km |
Source: NOAA IBTrACS (Category 1+, 1980–2026).
Tornado History
464 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF4. Total: 9 fatalities, 397 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Apr 28, 2002 | EF4 | 88 km | 38.0 mi | 3 |
| Sep 24, 2001 | EF3 | 51 km | 17.5 mi | 2 |
| Jul 19, 1996 | EF3 | 28 km | 2.2 mi | 0 |
| May 22, 1983 | EF3 | 40 km | 2.0 mi | 0 |
| Jun 7, 1980 | EF3 | 68 km | 1.5 mi | 0 |
| Sep 5, 1979 | EF3 | 64 km | 17.9 mi | 1 |
| Jan 26, 1978 | EF3 | 94 km | 0.7 mi | 1 |
| Apr 1, 1973 | EF3 | 61 km | 9.8 mi | 0 |
| Jun 9, 1961 | EF3 | 56 km | 0.1 mi | 0 |
| Apr 16, 1961 | EF3 | 82 km | 0.1 mi | 0 |
| Apr 5, 1952 | EF3 | 56 km | 17.5 mi | 0 |
| Sep 1, 2021 | EF2 | 78 km | 11.4 mi | 0 |
| Apr 19, 2019 | EF2 | 81 km | 2.9 mi | 0 |
| Nov 2, 2018 | EF2 | 6 km | 5.5 mi | 0 |
| Jul 23, 2017 | EF2 | 88 km | 2.4 mi | 0 |
| Apr 28, 2011 | EF2 | 89 km | 2.6 mi | 0 |
| Sep 18, 2004 | EF2 | 85 km | 2.0 mi | 0 |
| Sep 17, 2004 | EF2 | 93 km | 8.0 mi | 0 |
| Sep 17, 2004 | EF2 | 59 km | 15.0 mi | 0 |
| Sep 17, 2004 | EF2 | 27 km | 3.0 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Wildfire History
1 wildfire (100+ acres) recorded within 100 km. Largest: NCO (816 acres, 1999).
| Year | Name | Acres Burned | Distance |
| 1999 | NCO | 816 | 89 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 32°F (-0°C) | 2.8 in | Coldest |
| February | 33°F (1°C) | 2.7 in | Driest |
| March | 42°F (6°C) | 3.5 in | |
| April | 52°F (11°C) | 3.3 in | |
| May | 62°F (17°C) | 3.9 in | Wettest |
| June | 70°F (21°C) | 3.7 in | |
| July | 75°F (24°C) | 3.7 in | Warmest |
| August | 73°F (23°C) | 3.7 in | |
| September | 67°F (19°C) | 3.4 in | |
| October | 55°F (13°C) | 2.9 in | |
| November | 45°F (7°C) | 3.2 in | |
| December | 36°F (2°C) | 3.0 in |
Green Valley has a seasonal temperature swing of 43°F / from 32°F in January to 75°F in July. Total annual precipitation is 39.9 inches, with May being the wettest month (3.9") and February the driest (2.7").