North Charleston, South Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

978
FXUS62 KCHS 210650
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
250 AM EDT Wed Oct 21 2026

.WHAT HAS CHANGED...
All Key Messages and sections were updated.

&&

.KEY MESSAGES...
- 1) Below normal temperatures will continue this week as high
  pressure prevails and a powerful nor`easter gradually pulls
  away from the Mid-Atlantic coast.

- 2) Risk for minor coastal flooding through Thursday along
  coastal areas of Charleston and Colleton Counties. The highest
  astronomical tides of 2026, combined with near gale force
  northeast winds, will bring a multi-day coastal flooding and
  coastal hazards threat Friday into early next week.

&&

.DISCUSSION...
KEY MESSAGE 1: Below normal temperatures will continue this
week as high pressure prevails and a powerful nor`easter
gradually pulls away from the Mid-Atlantic coast.

Through Daybreak: The boundary layer has mostly decoupled inland
away from the coastal corridor with calm to light/variable winds
being reported across most observation platforms. Strong
radiational cooling is in progress with clear skies, calm/light
winds and a very dry airmass in place. A small patch of
cirrostratus associated with a passing shortwave is moving
across parts of the Charleston Tri-County, but no meaningful
impacts to temperature have been observed so far. 21/05z
temperatures were running about 3-7 degrees colder than the
21/01z NBM, which is not surprising given NBM`s well documented
warm bias in radiational cooling regimes. Early morning lows
were adjusted closer to a blend of the H3R and RAP which yields
mid-upper 40s inland to the upper 50s/near 60 at the beaches.

Today and Tonight: Large high pressure will maintain its
influence across the region through tonight. Other than a few
patches of thin high clouds moving through, mostly clear skies
will prevail. Low-level thickness schemes support highs in the
mid-upper 70s, which is pretty much in line with the various
guidance packages. The 21/01z NBM looks a tad too cool based on
highs observed over the past several afternoons and temperatures
at or just a degree or so above the third quartile in the
interquartile range (IQR) were favored based on a blend of the
latest high-res guidance.

The boundary layer will decouple quickly this evening resulting
in another round of calm/light winds. These winds combined with
ongoing clear skies and a continued dry airmass will support
strong radiational cooling. The NBM low temperature forecast
again looks too warm given how strong radiative processes will
be. Lows were heavily adjusted down as a result with another
blend closer to the H3R and RAP favored. Lows will range from
the lower-mid 40s inland to the upper 50s at the beaches. Some
spotty upper 30s can not be ruled out, especially in some of the
typical colder spots such as the Francis Marion National
Forest.

Thursday: A nor`easter will be located well off the Northeast
U.S. coast in the morning, while High pressure will be north of
the Great Lakes region, with it`s periphery stretching well into
the Southeast U.S. The nor`easter will quickly accelerate away
during the day, followed by the periphery of the High building
southwards into our region. This will bring our area dry
conditions with sunny skies. High temperatures are forecasted to
be in the middle to maybe upper 70s. However, the dry
conditions, clear skies, and light to calm winds at night will
cause decent radiational cooling. This will lead to low
temperatures that are several degrees below overnight.

Friday through Sunday: High pressure will strengthen over the
Mid- Atlantic States Friday while a coastal trough develops
along the Southeast U.S. coast, persisting through the weekend.
This will cause NE winds to increase and become gusty,
especially closer to the coast. While the High is expected to
prevail and keep it dry, there is the potential some showers
could make a run for the immediate coast before dissipating.
These details will get refined in future forecast. Otherwise,
temperatures may be several degrees below normal.


KEY MESSAGE 2: Risk for minor coastal flooding through Thursday
along coastal areas of Charleston and Colleton Counties. The
highest astronomical tides of 2026, combined with near gale
force northeast winds, will bring a multi-day coastal flooding
and coastal hazards threat Friday into early next week.

Tide levels in the Charleston Harbor are expected to peak near
7.0 ft MLLW (minor) during the late afternoon/early evening high
tide both today and again Thursday.

Tidal departures will begin to increase as northeast winds
strengthen along the coast on Saturday. Minor to moderate
coastal flooding is possible for Charleston and coastal Colleton
counties Saturday evening. Winds are forecast to strengthen to
near gale force on Sunday. Moderate to major coastal flooding is
possible for Charleston and Colleton counties, with moderate
coastal flooding possible along the southern SC and GA
coastlines.

The Perigean spring or King Tides will begin this weekend and
continue into early next week, the highest astronomical tides of
the year will occur Tuesday and Wednesday mornings. In fact,
the morning high in the Charleston Harbor will see astronomical
high tide values near 6.9 ft MLLW, just 0.1 ft below flood
stage. Ongoing gusty northeast winds and elevated tidal
departures may lead to coastal flooding for much of next week,
most likely during the morning high tide cycle. Fortunately, no
measurable rainfall is expected this weekend into early next
week.

In addition to coastal flooding, there is an increased risk for
a number of coastal hazards including high surf, beach erosion,
strong rip currents and breezy to windy conditions.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
21/06z TAFs:
KCHS/KJZI/KSAV: VFR through 22/06z.

Extended Aviation Outlook: Gusty northeast winds upwards of 25
kt are expected this weekend.

&&

.MARINE...
Through Tonight: Conditions are steadily improving across the
marine area early this morning. Both wind and sea observations
from area buoys indicate conditions have dropped below Small
Craft Advisory levels across the nearshore waters and the
advisories have been cancelled early. Seas of 3-5 ft across the
nearshore waters will subside to 2-4 ft this afternoon and
tonight. For the offshore waters, 5-7 ft seas this morning will
subside to 4-6 ft overnight. A Small Craft Advisory remains in
effect for the Georgia offshore leg. Overall, north/northeast
winds of 15-20 kt will prevail across the waters this morning
and will slowly diminish to 10-15 kt through the day and into
the overnight hours.

Thursday: A nor`easter will be located well off the Northeast
U.S. coast in the morning, while High pressure will be north of
the Great Lakes region, with it`s periphery stretching well into
the Southeast U.S. The nor`easter will quickly accelerate away
during the day, followed by the periphery of the High building
southwards into our region. Expect NE winds during the day and
into the evening, then gradually increasing overnight. Lingering
6+ ft seas will cause the Small Craft Advisory for the 20-60 nm
GA waters to remain in effect.

Friday through Sunday: High pressure will strengthen over the
Mid- Atlantic States Friday while a coastal trough develops
along the Southeast U.S. coast, persisting through the weekend.
The interaction between these two features will cause marine
conditions to rapidly deteriorate Friday. Winds and seas will
substantially increase, first necessitating a period of Small
Craft Advisories on Friday (including the Charleston Harbor),
and then Gale headlines likely for all of our Atlantic waters
Friday night into the weekend. Models hint that strong gale
conditions are possible, so more significant refinements will
be needed for the weekend portion of the wind and wave forecast.

Rip Currents:
Today: Lingering long period swell directed into the Georgia
will support a moderate risk for rip currents through tonight
from Tybee Island to Sapelo Island.

Thursday: There is a Moderate Risk for our GA beaches.

Friday through Sunday: The combination of gales developing in
the coastal waters and building seas will lead to an elevated
risk of rip currents at all of our beaches.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory until 6 AM EDT Monday for AMZ384.

&&

$$