Charleston Harbor Marine Forecast
| Tonight...W Winds 10 To 15 Kt. |
| Fri...W Winds 5 To 10 Kt. |
| Fri Night...Nw Winds 5 To 10 Kt. |
| Sat...N Winds 5 Kt, Becoming Ne In The Afternoon. |
| Sat Night...Ne Winds 5 Kt. |
| Sun...Ne Winds 5 To 10 Kt. |
| Sun Night...Ne Winds 10 Kt. A Chance Of Showers. A Chance Of Tstms After Midnight. |
| Mon...N Winds 10 To 15 Kt. A Chance Of Showers And Tstms. |
| Mon Night...N Winds 10 To 15 Kt. A Slight Chance Of Showers. |
| Tue...N Winds 10 To 15 Kt. |
| Tue Night...Ne Winds 5 To 10 Kt. Winds And Waves Higher In And Near Tstms. Unless Otherwise Noted, Waves 1 Foot Or Less. Charleston Harbor Water Temperature 65 Degrees. |
| Area Forecast Discussion National Weather Service Charleston SC 1054pm EDT Thu Oct 30 2025 Synopsis Cool and dry high pressure will build across the region tonight and will linger through this weekend. A low pressure system could impact the area early next week. Near Term - Until 6am Friday Morning Strong high pressure will expand over the area through tonight. The departing surface low is now well northeast of the area, however broken stratocumulus associated with its comma head has been expanding into the area from the west. All guidance indicates this cloud cover should dissipate by late this evening, resulting in clear skies overnight. Decent west winds will continue through the early overnight hours, then diminish late. The decreasing surface winds in concert with clearing skies will allow surface temps to rapidly drop off later tonight. Friday morning lows could dip into the lower 40s inland. Short Term - 6am Friday Morning Through Sunday An area of surface high pressure will be meandering around the southeast, the cool and dry conditions will continue into and throughout most of the weekend. Expect the highs on Friday to be in the mid to upper 60s. As the surface pressure gradient relaxes throughout the day on Friday, expect the breezy west-northwest winds to subside, setting the stage for a strong radiational cooling setup as skies remain clear and a modest temperature inversion occurs. Overnight low temperatures from the deterministic NBM continue to run a couple degrees too warm, while at the same time providing 50 percent or greater probabilities of reaching temperatures at or below 38, particularly for inland southeast South Carolina and southeast Georgia. So, in coordination with surrounding offices, did mix in some cooler guidance to account for those probabilities, which then also allows/continues patchy frost to be represented in the forecast. Does not look like we'll see temperatures dip below 36, as probabilities similarly drop into the 30 percent range for temperatures at or below 36 degrees, so not anticipating a Frost Advisory at this time. For areas along the coast, overnight lows Otherwise, expect daily high temperatures this weekend in the mid 60s to lower 70s. Overnight temperatures Saturday into Sunday rise into the lower 40s inland and mid 50s along the coast. An upper level trough begins to move towards the region from the deep south on Sunday, increasing cloud coverage as mid/upper level moisture levels rise. Long Term - Sunday Night Through Thursday Sunday night into Monday, the aforementioned trough continues to approach the area from the west, with the northern part of energy likely moving through the region by Monday afternoon, while the southern part may break off into a closed off upper level low. That alone introduces a great deal of uncertainty as model agreement, in both the deterministic and ensemble space, regarding the placement/timing/strength of the trough is low/moderate. In addition, deterministic and ensemble guidance thus are having trouble agreeing on where surface cyclogenesis takes place, and thus where the bulk of the rain will fall. The two leading Quantitative Precipitation Forecast ensemble clusters would suggest the bulk of the rain will fall either across easter North Carolina, or well off to sea, while the trailing third solution (only representing 15% of ensembles) gives the bulk of the precipitation over eastern South Carolina, and lower amounts in southeast Georgia. The NBM covers this uncertainty well only carrying a 20-30% chance for scattered showers and isolated thunderstorms, starting late Sunday evening and ending late Monday evening, though based on the previous clustering analysis we may be seeing a decreasing trend in precipitation potential. Temperatures throughout the time period look to remain in the mid 60s to lower 70s, with overnight lows in the mid 40s to mid 50s. Surface high pressure builds into the region into Tuesday, continuing the cooler temperatures, while also bringing marginally-breezy conditions along with it. Marine The NW flow will continue to slowly subside through tonight, with seas also starting to come down. Gusts in Charleston Harbor could get close to 20 kt through late evening. Small Craft Advisories continue for waters off the Charleston County Coast and outer Georgia waters through the night, where west winds gust upwards to 25-30 kt (highest across outer Georgia waters) and seas generally range between 4-7 ft (largest across outer Georgia waters). Friday through Monday: High pressure will build over the marine zones on Friday, winds decreasing to around 10 kts. Wave heigheights should subside during the day, falling below 6 ft Friday morning. Small Craft Advisories will be expiring throughout the day on Friday. High pressure will provide benign conditions through this weekend. Low pressure will begin to develop east of the region on Monday, remaining near the region into Wednesday. As a result, winds and wave heigheights should increase on Monday and Tuesday. Gusty winds and building seas may require Small Craft Advisories starting over portions of the waters on Monday. Rip Currents Modest swell energy will continue a moderate rip current risk on Friday for all beaches. For Saturday, a low rip current risk is expected at all beaches. Tides / Coastal Flooding King tides return early next week. Coastal flooding impacts are possible, but details are uncertain. NOAA Charleston SC Office: Watches - Warnings - Advisories GA...None. SC...None. Marine Small Craft Advisory until 4pm EDT Friday for AMZ350-374. |
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