Charleston Harbor Marine Forecast
| Today...Sw Winds 5 To 10 Kt, Becoming S 10 To 15 Kt With Gusts To 20 Kt This Afternoon. |
| Tonight...Sw Winds 10 To 15 Kt. |
| Fri...Sw Winds 5 To 10 Kt. |
| Fri Night...Sw Winds 5 To 10 Kt. |
| Sat...Sw Winds 5 To 10 Kt. |
| Sat Night...S Winds 10 Kt. |
| Sun...W Winds 10 To 15 Kt. |
| Sun Night...N Winds 10 To 15 Kt, Increasing To 15 To 20 Kt. Waves Building 1 To 2 Ft. |
| Mon...Ne Winds 10 To 15 Kt. |
| Mon Night...Ne Winds 5 To 10 Kt. Unless Otherwise Noted, Waves 1 Foot Or Less. Charleston Harbor Water Temperature 69 Degrees. |
| Area Forecast Discussion National Weather Service Charleston SC Issued by National Weather Service Wilmington NC 230pm EDT Monday August 17 2026 .WHAT HAS CHANGED... Extreme Heat Warnings and Heat Advisories have been issued for dangerous heat on Tuesday. .KEY MESSAGES... - 1) Heat will remain a concern through the middle of the week. - 2) Some strong to severe thunderstorms are possible each afternoon this week. KEY MESSAGE 1: Heat will remain a concern through the middle of the week. This Afternoon and Evening: Hot and oppressive conditions will continue this afternoon and gradually come to an end early this evening. Visible satellite shows the effects of the expansive ridge and dry air aloft. Bubbling cumulus over extreme southeastern SC and southeastern GA converging with the struggling sea breeze is the only hint a the potential for a stray shower or thunderstorm late this afternoon. Heat headlines remain in effect for the entire through this evening. Tuesday: Hot/humid conditions will remain across the Southeast United States with large-scale ridging centered across the Deep South and northern Gulf regions. Record warmth is possible, especially as the heat wave peaks with another day of favorable downslope flow across the local area. Many areas could see temps peak around 100 degrees along the I-95 corridor as afternoon convection is limited. The setup favors some mixing out of surface dewpts across inland areas, but moisture pooling along/near an afternoon sea breeze supports surface dewpts in the mid-upper 70s. An Extreme Heat Warning has been issued for areas along and east of I- 95. Latest probabilistic guidance supports slightly higher dew points on Tuesday, therefore the Extreme Heat Warning has been expanded a row of counties inland across the SC Lowcountry and southeastern GA. Wednesday into Friday: There are signs of the expansive ridge starting to weaken while scattered convection returns during peak heating hours mid to late week. We could see Heat Advisory conditions prior to showers/thunderstorms developing Wednesday and Thursday, especially along the coastal corridor. Friday remains warm, but guidance supports greater convective coverage and some relief from the heat during peak heating hours, as shortwave energy associated with a large-scale trough approaches the Mid-Atlantic and Southeast states this weekend. KEY MESSAGE 2: Some strong to severe thunderstorms are possible each afternoon this week. The heat and humidity mentioned in Key Message 1 will provide instability across our area each afternoon this week. While each model has differences regarding how much will be in place and where the highest values will be, the general consensus seems to be SBCAPE values in the 2,000-3,000 J/kg range with locally higher peaks. DCAPE values should easily exceed 1,000 J/kg. There are notable differences between the various CAMS and the deterministic models, with many pointing to it being dry each afternoon or minimal convection. However, the amount of instability in place is hard to ignore. Likewise, it won't take much for isolated to scattered convection to form along the sea breeze each afternoon and then shift inland. Therefore, we raised POPs each afternoon, generally going with slight chance to chance. The outflow and boundary interactions should play a major role in additional storm formation and persistence. Strong to severe thunderstorms are possible each afternoon with the main threat being damaging winds. Heavy rainfall is also a concern due to the very weak steering winds and elevated PWATs. Backbuilding and/or training of storms could drop enough rainfall to generate very localized flooding. Any convection should dissipate each evening with the setting sun. Marine Tonight and Tuesday: Winds remain elevated overnight, gusting up to 20 knots at times. Typical summertime winds continue into Tuesday. Similar conditions are expected on Tuesday afternoon with the strongest winds near the sea breeze. Seas will average 2-3 ft within 20 nm and 3-4 ft in the 20-60 nm leg. Extended Marine: There will be areas of high pressure in the western Atlantic and the northern Gulf, while surface troughing persists over the Southeast United States. The interaction between these synoptic features will support a typical summertime wind pattern with winds/seas that remain below Small Craft Advisory levels. In general, southwest winds should back to a more south direction each day, peaking in speed along the coast due to a sea breeze, then return to southwest during the overnight period. Seas will mainly be in the 2-3 ft range. NOAA Charleston SC Office: Watches - Warnings - Advisories GA... Heat Advisory until 8pm EDT this evening for GAZ087-088- 099>101-114-115-137-216-218-238. Heat Advisory from 11am to 8pm EDT Tuesday for GAZ087-088- 099-100-114-115-137. Extreme Heat Warning from 11am to 8pm EDT Tuesday for GAZ101- 216>219-238>241. Extreme Heat Warning until 8pm EDT this evening for GAZ217- 219-239>241. SC... Heat Advisory until 8pm EDT this evening for SCZ040-042>044- 147. Heat Advisory from 11am to 8pm EDT Tuesday for SCZ040-042- 043. Extreme Heat Warning from 11am to 8pm EDT Tuesday for SCZ044- 045-147>152. Extreme Heat Warning until 8pm EDT this evening for SCZ045- 148>152. Marine None. |
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