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Weather & Climate in Johnston, SC
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Johnston enjoys a temperate climate with an average annual temperature of 63°F (17°C). Winters average 44°F in January while summers reach 81°F in July. The area gets 308 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 48.5 inches (wetter than the 38-inch national average). Air quality is rated Good with a median AQI of 43. The city sits at an elevation of 640 feet.
Temperature
44°F Jan (7°C)
81°F Jul (27°C)
| Annual Average | 62.7°F |
| 16% above US avg | |
| January Average | 44°F (7°C) |
| July Average | 81°F (27°C) |
| Sunny Days | 308 days/yr |
Geography
| Elevation | 640 ft (195 m) |
| Area | 2.7 sq mi (6.9 km²) |
| Population Density | 961/sq mi |
| Coordinates | 33.8334°N, 81.8048°W |
| Timezone | America/New_York |
| County | Edgefield County County |
| Nearest Airport | Aiken Regional (AIK) 14 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 43.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Very Low |
| Risk Score | 22.0 / 100 |
| Social Vulnerability | 54.7 / 100 |
| Community Resilience | 21.3 / 100 |
Hazard Breakdown
| Tornado | Relatively Low |
| Hurricane | Relatively Low |
| Earthquake | Relatively Low |
| Wildfire | Very Low |
| Flood | Very Low |
| Hail | Relatively Low |
| Strong Wind | Relatively Low |
| Heat Wave | Relatively Low |
| Winter Weather | Very Low |
| Lightning | Relatively Low |
| Ice Storm | Relatively Moderate |
| Drought | Relatively Low |
| Cold Wave | Relatively Low |
| Landslide | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
44 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M4.1.
| Feb 15, 2014 | 12 km ENE of Parksville, South Carolina | M4.1 | 27 km | 5 km |
| Apr 13, 1998 | 9 km S of Kershaw, South Carolina | M3.9 | 131 km | 7 km |
| Jun 29, 2022 | 6 km E of Elgin, South Carolina | M3.6 | 106 km | 3 km |
| Jun 29, 2022 | 6 km E of Elgin, South Carolina | M3.5 | 106 km | 3 km |
| Mar 18, 2003 | 11 km S of Rayle, Georgia | M3.5 | 101 km | 5 km |
| Jan 3, 1992 | 4 km ENE of Willington, South Carolina | M3.4 | 59 km | 3 km |
| Jun 26, 2022 | 6 km E of Elgin, South Carolina | M3.4 | 106 km | 4 km |
| May 9, 2022 | 5 km ESE of Elgin, South Carolina | M3.3 | 105 km | 4 km |
| Jun 20, 2017 | 6 km SW of Augusta, Georgia | M3.2 | 49 km | 13 km |
| Dec 7, 2009 | 4 km WNW of Deepstep, Georgia | M3.2 | 143 km | 7 km |
| Aug 8, 1993 | 12 km ENE of Aiken, South Carolina | M3.2 | 33 km | 9 km |
| Apr 4, 2009 | 15 km N of Milledgeville, Georgia | M3.1 | 147 km | 0 km |
| Aug 23, 2025 | 3 km N of Coronaca, South Carolina | M3.0 | 57 km | 2 km |
| Feb 16, 2014 | 13 km WNW of Edgefield, South Carolina | M3.0 | 24 km | 7 km |
| Feb 18, 2005 | 7 km ENE of Irmo, South Carolina | M2.9 | 71 km | 1 km |
| Aug 23, 2025 | 3 km NNW of Coronaca, South Carolina | M2.9 | 58 km | 7 km |
| Apr 26, 2013 | 9 km E of Lincolnton, Georgia | M2.8 | 53 km | 12 km |
| Sep 18, 1996 | 6 km E of Clarks Hill, South Carolina | M2.8 | 33 km | 14 km |
| May 10, 2022 | 5 km E of Elgin, South Carolina | M2.8 | 106 km | 2 km |
| Apr 6, 2017 | 6 km WSW of Sparta, Georgia | M2.7 | 131 km | 11 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Hurricane History
9 hurricanes (Category 1+) recorded within 500 km since 1980. Strongest on record: Category 4.
| Year | Name | Category | Max Wind | Closest |
| 2022 | Ian | Category 1 | 86 mph | 249 km |
| 2020 | Isaias | Category 1 | 92 mph | 276 km |
| 2019 | Dorian | Category 3 | 115 mph | 298 km |
| 2018 | Michael | Category 1 | 92 mph | 275 km |
| 2016 | Matthew | Category 2 | 98 mph | 228 km |
| 2004 | Charley | Category 1 | 81 mph | 242 km |
| 2004 | Gaston | Category 1 | 75 mph | 225 km |
| 1989 | Hugo | Category 4 | 138 mph | 116 km |
| 1985 | Bob | Category 1 | 75 mph | 219 km |
Source: NOAA IBTrACS (Category 1+, 1980–2026).
Tornado History
451 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF4. Total: 31 fatalities, 520 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Mar 28, 1984 | EF4 | 75 km | 21.0 mi | 5 |
| Dec 13, 1973 | EF4 | 43 km | 1.0 mi | 2 |
| Mar 31, 1973 | EF4 | 76 km | 22.6 mi | 7 |
| Apr 5, 2022 | EF3 | 98 km | 34.5 mi | 0 |
| Apr 13, 2020 | EF3 | 69 km | 35.7 mi | 2 |
| Apr 13, 2020 | EF3 | 85 km | 5.4 mi | 0 |
| Apr 13, 2020 | EF3 | 75 km | 1.4 mi | 0 |
| Apr 13, 2020 | EF3 | 63 km | 37.9 mi | 0 |
| Apr 13, 2020 | EF3 | 67 km | 8.5 mi | 0 |
| Apr 10, 2009 | EF3 | 59 km | 17.7 mi | 0 |
| Apr 10, 2009 | EF3 | 87 km | 26.3 mi | 0 |
| Apr 10, 2009 | EF3 | 47 km | 14.6 mi | 0 |
| Mar 15, 2008 | EF3 | 44 km | 27.5 mi | 0 |
| Dec 10, 2004 | EF3 | 95 km | 1.5 mi | 0 |
| May 7, 1998 | EF3 | 31 km | 12.0 mi | 1 |
| May 7, 1998 | EF3 | 21 km | 5.0 mi | 0 |
| Nov 2, 1995 | EF3 | 65 km | 1.5 mi | 0 |
| Aug 16, 1994 | EF3 | 92 km | 30.0 mi | 0 |
| Aug 16, 1994 | EF3 | 54 km | 8.0 mi | 0 |
| Aug 16, 1994 | EF3 | 52 km | 0.3 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Wildfire History
20 wildfires (100+ acres) recorded within 100 km. Largest: UNNAMED (8,427 acres, 2009).
| Year | Name | Acres Burned | Distance |
| 2009 | UNNAMED | 8,427 | 61 km |
| 2009 | UNNAMED | 5,322 | 93 km |
| 2014 | UNNAMED | 3,897 | 35 km |
| 2019 | UNNAMED | 3,772 | 36 km |
| 2010 | C-94-95 133 RX | 3,192 | 72 km |
| 2009 | UNNAMED | 3,165 | 62 km |
| 2010 | UNNAMED | 2,968 | 57 km |
| 2010 | UNNAMED | 2,909 | 69 km |
| 2021 | C-326/327 LC | 2,852 | 36 km |
| 2010 | UNNAMED | 2,796 | 75 km |
| 2008 | UNNAMED | 2,711 | 76 km |
| 2015 | UNNAMED | 2,690 | 87 km |
| 2013 | UNNAMED | 2,654 | 30 km |
| 2010 | UNNAMED | 2,532 | 36 km |
| 2017 | UNNAMED | 2,514 | 80 km |
| 2009 | UNNAMED | 2,458 | 84 km |
| 2008 | UNNAMED | 2,407 | 75 km |
| 2017 | UNNAMED | 2,395 | 88 km |
| 2017 | UNNAMED | 2,362 | 87 km |
| 2010 | UNNAMED | 2,330 | 68 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 44°F (7°C) | 4.8 in | Coldest |
| February | 46°F (8°C) | 4.0 in | |
| March | 54°F (12°C) | 4.8 in | Wettest |
| April | 61°F (16°C) | 3.2 in | |
| May | 69°F (20°C) | 3.6 in | |
| June | 76°F (25°C) | 4.3 in | |
| July | 81°F (27°C) | 4.7 in | Warmest |
| August | 78°F (26°C) | 4.3 in | |
| September | 73°F (23°C) | 3.5 in | |
| October | 62°F (17°C) | 3.4 in | |
| November | 53°F (12°C) | 3.0 in | Driest |
| December | 45°F (7°C) | 3.6 in |
Johnston has a seasonal temperature swing of 37°F / from 44°F in January to 81°F in July. Total annual precipitation is 47.2 inches, with March being the wettest month (4.8") and November the driest (3.0").