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Weather & Climate in Ashton-Sandy Spring, MD
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Ashton-Sandy Spring enjoys a temperate climate with an average annual temperature of 57°F (14°C). Winters average 34°F in January while summers reach 79°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 47.5 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 488 feet.
Temperature
34°F Jan (1°C)
79°F Jul (26°C)
| Annual Average | 57.1°F |
| 6% above US avg | |
| January Average | 34°F (1°C) |
| July Average | 79°F (26°C) |
| Sunny Days | 293 days/yr |
Geography
| Elevation | 488 ft (149 m) |
| Area | 2.9 sq mi (7.6 km²) |
| Population Density | 528/sq mi |
| Coordinates | 39.1487°N, 76.9991°W |
| Timezone | America/New_York |
| County | Howard County County |
| Nearest Airport | Baltimore/Washington International Thurgood Marshall (BWI) 18 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 41.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively Low |
| Risk Score | 72.4 / 100 |
| Social Vulnerability | 10.6 / 100 |
| Community Resilience | 92.9 / 100 |
Hazard Breakdown
| Tornado | Relatively Low |
| Hurricane | Relatively Low |
| Earthquake | Relatively Low |
| Wildfire | Very Low |
| Flood | Relatively Moderate |
| Hail | Relatively Low |
| Strong Wind | Relatively High |
| Heat Wave | Relatively Moderate |
| Winter Weather | Relatively High |
| Lightning | Relatively High |
| Ice Storm | Relatively Low |
| Drought | Relatively Moderate |
| Cold Wave | Relatively Low |
| Landslide | Very Low |
| Coastal Flood | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
22 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 | 38 km | 7 km |
| Jun 13, 2019 | 9 km N of Blain, Pennsylvania | M3.4 | 148 km | 27 km |
| Oct 23, 1990 | 3 km W of Hancocks Bridge, New Jersey | M3.2 | 135 km | 10 km |
| Jun 3, 2010 | 4 km ENE of Franklintown, Pennsylvania | M3.1 | 104 km | 2 km |
| Jan 17, 2016 | 3 km NE of Ranson, West Virginia | M3.0 | 74 km | 5 km |
| Nov 14, 1997 | 0 km S of Rothsville, Pennsylvania | M3.0 | 128 km | 5 km |
| Apr 24, 2009 | 1 km S of Franklintown, Pennsylvania | M2.9 | 102 km | 1 km |
| Sep 15, 2019 | 5 km ESE of East Berlin, Pennsylvania | M2.8 | 87 km | 5 km |
| Jul 1, 2009 | 3 km ESE of Pennsville, New Jersey | M2.8 | 142 km | 5 km |
| Oct 25, 2009 | 4 km ENE of Franklintown, Pennsylvania | M2.8 | 105 km | 1 km |
| Mar 15, 1993 | 5 km W of Columbia, Maryland | M2.7 | 13 km | 5 km |
| Oct 28, 1994 | 1 km E of Mount Vernon, Maryland | M2.7 | 38 km | — |
| Mar 11, 1995 | 0 km ENE of Landisville, Pennsylvania | M2.7 | 118 km | 5 km |
| Jan 25, 2015 | 4 km ESE of Downingtown, Pennsylvania | M2.6 | 149 km | 2 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 | 30 km | 3 km |
| Jan 18, 1994 | 3 km SE of Clay, Pennsylvania | M2.6 | 134 km | 5 km |
| Oct 28, 1996 | 2 km W of Reinholds, Pennsylvania | M2.6 | 145 km | 5 km |
| Sep 29, 1997 | Virginia | M2.5 | 53 km | 3 km |
| Jun 25, 2001 | 8 km S of Remington, Virginia | M2.5 | 105 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 | 209 km |
| 2003 | Isabel | Category 1 | 75 mph | 279 km |
| 1999 | Floyd | Category 1 | — | 273 km |
| 1986 | Charley | Category 1 | 81 mph | 250 km |
| 1985 | Gloria | Category 2 | 98 mph | 232 km |
Source: NOAA IBTrACS (Category 1+, 1980–2026).
Tornado History
493 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF4. Total: 9 fatalities, 395 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Apr 28, 2002 | EF4 | 68 km | 38.0 mi | 3 |
| Sep 17, 2004 | EF3 | 99 km | 9.0 mi | 0 |
| Sep 24, 2001 | EF3 | 24 km | 17.5 mi | 2 |
| Jul 19, 1996 | EF3 | 39 km | 2.2 mi | 0 |
| May 22, 1983 | EF3 | 65 km | 2.0 mi | 0 |
| Jun 7, 1980 | EF3 | 87 km | 1.5 mi | 0 |
| Sep 5, 1979 | EF3 | 42 km | 17.9 mi | 1 |
| Jan 26, 1978 | EF3 | 77 km | 0.7 mi | 1 |
| Apr 1, 1973 | EF3 | 48 km | 9.8 mi | 0 |
| Jun 9, 1961 | EF3 | 33 km | 0.1 mi | 0 |
| Apr 5, 1952 | EF3 | 72 km | 17.5 mi | 0 |
| Sep 1, 2021 | EF2 | 48 km | 11.4 mi | 0 |
| Nov 2, 2018 | EF2 | 27 km | 5.5 mi | 0 |
| Jul 23, 2017 | EF2 | 60 km | 2.4 mi | 0 |
| May 8, 2008 | EF2 | 99 km | 3.4 mi | 0 |
| Sep 18, 2004 | EF2 | 82 km | 2.0 mi | 0 |
| Sep 17, 2004 | EF2 | 82 km | 13.0 mi | 0 |
| Sep 17, 2004 | EF2 | 69 km | 4.0 mi | 0 |
| Sep 17, 2004 | EF2 | 90 km | 8.0 mi | 0 |
| Sep 17, 2004 | EF2 | 55 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 | 74 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 34°F (1°C) | 3.3 in | Coldest |
| February | 35°F (2°C) | 2.9 in | Driest |
| March | 44°F (7°C) | 3.9 in | |
| April | 54°F (12°C) | 3.5 in | |
| May | 63°F (17°C) | 4.6 in | Wettest |
| June | 72°F (22°C) | 3.8 in | |
| July | 79°F (26°C) | 4.2 in | Warmest |
| August | 75°F (24°C) | 3.9 in | |
| September | 68°F (20°C) | 4.1 in | |
| October | 57°F (14°C) | 3.5 in | |
| November | 47°F (8°C) | 3.7 in | |
| December | 38°F (3°C) | 3.4 in |
Ashton-Sandy Spring has a seasonal temperature swing of 45°F / from 34°F in January to 79°F in July. Total annual precipitation is 44.7 inches, with May being the wettest month (4.6") and February the driest (2.9").