A bitterly cold Arctic air mass persisted over the state for the entire week. Based on average temperature, 2018 began with the coldest first January week in 130 years of record keeping. Greenville-Spartanburg's average temperature for the first week of 2018 was 23.6 degrees, surpassing the old record of 29.3 degrees set in 1900. Columbia's average temperature was 27.9 degrees. Columbia's previous record average temperature for the same period was 31.3 degrees in 1928. Charleston also surpassed its 1928 35.3-degree record, shivering through a weekly average temperature of 27.3 degrees. Numerous date record low temperatures were set daily across the state. Several notable examples are provided in the table below.
| Date | Location | New Date Record | Old Date Record, Year |
|---|---|---|---|
| January 1 | Greenville (GSP) | 15 | 16, 1977 |
| January 2 | Santuck | 5 | 8, 1900 |
| January 3 | Jocassee | 3 | 13, 2010 |
| January 4 | Winnsboro | 9 | 12, 1928 |
| January 5 | Charleston (CHS) | 14 | 16, 1981 |
| January 6 | Table Rock | 8 | 12, 2010 |
| January 7 | Darlington | 10 | 12, 1924 |
New Year's Day was clear, cold and dry. Sassafras Mountain reported a morning low temperature of 5.4 degrees. Columbia, Orangeburg and Charleston reached an afternoon high temperature of 34 degrees. Tuesday morning, Jocassee reported a morning low temperature of 3 degrees that "warmed" to 26 degrees that afternoon.
On Wednesday, January 3, a rapidly deepening offshore low pressure system and provided moisture aloft for a major snow event for the state. Freezing rain began early over Beaufort County before transitioning to snow before noon. Heavy snow along I-95 snarled interstate traffic. I-95 was rendered "impassible" along 80-mile an snow and ice choked path from Mile Marker 77 in Dorchester County to the Georgia State Line until Friday, January 5. Snowfall was heaviest at the coast, and as the offshore low deepened, convective banding developed that brought 3-6 inches of snow north into Marlboro, Dillon, and Marion counties. East of the banding Horry County was spared the , 0.10-0.25 inches of ice and 0.2 inches of snow were reported along the Grand Strand. With frigid Arctic air in place over the state little melting occurred. Black ice was a new and nightly threat to South Carolina motorists. The runways at the Charleston Air Force Base, that received 5.3 inches of snow Wednesday, were closed until Sunday, January 7. The Charleston NWS Office reported 2 inches of snow remained on the ground at the end of the week. The table below shows the range of snowfall amounts, official and unofficial:
| Snowfall (in.) | Snowfall (in.) | |||
|---|---|---|---|---|
| Summerville | 7.3 | Johns Island | 3.9 | |
| Moncks Corner | 6.5 | Cainhoy | 3.5 | |
| Sumter | 6.1 | Bowman | 3.0 | |
| Ridgeville | 5.4 | Dillon | 3.0 | |
| Charleston AFB | 5.3 | James Island | 3.0 | |
| Orangeburg | 5.0 | Florence | 2.5 | |
| Bishopville | 5.0 | Awendaw | 2.0 | |
| Mount Pleasant | 4.8 | Cheraw | 1.0 | |
| Hilton Head Island | 4.5 | Bamberg | 0.5 | |
| Yemassee | 4.0 | Columbia Metro | Trace |
Skies cleared rapidly as the offshore nor'easter rocketed to New England. With snow covered ground, Bishopville reported a morning low of 6 degrees on January 4. Columbia' afternoon temperature reached 42 degrees, while Charleston only warmed to 37 degrees after a morning low of 17 degrees. Anderson, Orangeburg and Columbia had high temperatures of 42 degrees on Friday. A reinforcing shot of more Arctic air arrived for the weekend to prolong the frigid temperatures for the state. Saturday, Caesars Head had a morning low temperature of 5 degrees, and by Sunday, Union had a low temperature of 4 degrees. Sunday's high temperature reached 35 degrees in Columbia and 37 degrees in Charleston.
(Note: The highest and lowest official temperatures and highest precipitation totals provided below are based on observations from the National Weather Service Cooperative Observer network and the National Weather Service's Forecast Offices.)
The highest official temperature reported was 47 degrees at the Barnwell 5 ENE NWS COOP site on January 5.
The lowest official temperature reported was 3 degrees at Jocassee on January 2.
The heaviest official 24-hour precipitation reported was 1.14 inches at the Charleston Air Force Base on January 3.
The state average precipitation for the seven-day period was 0.2 inches.
| Weekly* | Since Jan 1 | Departure | |
|---|---|---|---|
| Anderson Airport | 0.00 | 0.00 | -0.9 |
| Greer Airport | 0.00 | 0.00 | -0.9 |
| Charlotte, NC Airport | 0.00 | 0.00 | -0.8 |
| Columbia Metro Airport | 0.00 | 0.00 | -0.8 |
| Orangeburg Airport | 0.04 | 0.04 | -0.9 |
| Augusta, GA Airport | 0.00 | 0.00 | -0.9 |
| Florence Airport | 0.10 | 0.10 | -0.6 |
| North Myrtle Beach Airport | 0.06 | 0.06 | -0.8 |
| Charleston Air Force Base | 1.14 | 1.14 | 0.3 |
| Savannah, GA Airport | 0.24 | 0.24 | -0.5 |
| *Weekly precipitation totals ending midnight Sunday. |
4-inch depth soil temperature: Clinton: 36 degrees. Columbia: 42 degrees. Barnwell: 33 degrees. Mullins: 19 degrees
Upstate river stages were below normal to much below normal.
Midlands and Pee Dee river stages were below normal to much below normal .
Lowcountry river stages were normal.
Charleston Harbor water temperature: 41.5 degrees.
Fripp Nearshore Buoy (Station 41033): 45.0 degrees.
