North Charleston, South Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

586
FXUS62 KCHS 231811
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
211 PM EDT Wed Sep 23 2026

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

&&

.KEY MESSAGES...
- 1) Breezy and cooler weather will persist into the weekend.

- 2) The coastal flood risk ramps up through Friday due to
  persistent northeast winds and high astronomical tides.

- 3) High risk of dangerous rip currents Thursday across all
  South Carolina and Georgia beaches.

&&

.DISCUSSION...
KEY MESSAGE 1: Breezy and cooler weather will persist into the
weekend.

Through Tonight: Impressive cold air damming (CAD) for early
Fall continues to strengthen this afternoon with surface
cyclogenesis occurring well offshore of the Carolina coast. This
is leading to breezy conditions at the beaches with temperatures
across the Lowcountry and Southeast Georgia running well below
normal for late September. This is certainly a welcome change
from brutal heat that the region has experienced for most of the
summer. As is typical for CAD events, the NBM is verifying
horribly and was running ~10 degrees too warm as of 23/17z.
This trend will persist into the rest of the afternoon with
temperatures poised to only top out in mid 70s for areas well
inland closer to the CSRA and the Southern Midlands to the lower
80s south of the I-16 corridor. A few showers embedded in the
northeast low-level flow could brush portions of McIntosh
County from off the Atlantic, otherwise dry conditions will
prevail. Breezy conditions will linger into tonight at the
beaches with gusts 25-30 mph at times. The inland wedge will
tighten up even more tonight as low offshore deepens. Lows will
range from the mid 60s well inland to the lower 70s at the
beaches.

Thursday: The wedge will be at its strongest during this time
as the developing nor`easter offshore moves north of Cape
Hatteras and its broad, cyclonic flow helps to reinforce the
CAD. Pinning down high temperatures for Thursday proved
especially tricky where a passing shortwave rounding the base of
the upper low combined with increased UVVs with the left exit
region of the polar jet could produce scattered showers, mainly
from late morning on. This could induce quite a bit of diabatic
cooling given a cool/dry northeast flow that will be in place,
especially over the Lowcountry. Highs were nudged closer to the
lower side of the NBM interquartile range (IGR) and blended with
some of the colder high-res direct model output. This yields
highs from the lower 70s well inland to the mid-upper 70s
elsewhere, warmest closer to the Altamaha River. Pops range from
30-50% across the Charleston Tri-County to 20% for far southern
South Carolina with <10% over Southeast Georgia. Thursday night
looks somewhat chilly with overnight lows expected to drop into
the mid-upper 50s inland to the mid 60s at the beaches.

Friday into Sunday: The wedge will begin to weaken Friday and
steadily break down through the weekend as the nor`easter moves
closer to New England. Temperatures will gradually moderate
through the period.


KEY MESSAGE 2: The coastal flood risk ramps up through Friday
due to persistent northeast winds and high astronomical tides.

Breezy northeasterly flow combined with the upcoming full moon
(9/26) will yield an increase in tidal departures across the
region.

Charleston and Colleton County: With the ongoing environmental
conditions, tidal levels could reach 7.1 ft MLLW in the
Charleston Harbor for this evening`s high tide (approx. at
628PM). Therefore, Coastal Flood Advisory has been issued from
5PM to 8PM this evening. Saltwater inundation will be possible
1-2 hours before and after high tide, and will likely result in
some roads becoming impassable.

Coastal flooding concerns will then ramp up on Thursday and
Friday, with the potential to reach moderate flood stage along
the Charleston and Colleton County coastlines each evening.
Additionally, guidance indicates the Friday morning high tide
could see minor coastal flooding.

Lower South Carolina and Southeast Georgia: Tidal levels could
reach 8.8 ft MLLW for this evening`s high tide in Fort Pulaski,
thus this keeps conditions just below minor flood stage.
However, the Thursday and Friday evening`s high tide forecast
indicates potential to reach minor flood stage (9.5 ft MLLW).
This would prompt a Coastal Flood Advisory for Lower South
Carolina and Southeast Georgia for Thursday and Friday evening,
however conditions will continue to monitored over the next 24
hours.

KEY MESSAGE 3: High risk of dangerous rip currents Thursday
across all South Carolina and Georgia beaches.

Strengthening low pressure well off the mid-Atlantic coast will
support breezy winds, building wave heights, and large swells
with a 7-8 second period along the coast on Thursday. This setup
will drive a High Risk for rip currents along the entire South
Carolina and Georgia coastline on Thursday. An elevated risk for
rip currents will persist Friday into the weekend due to
incoming longer period (10-12 second) swell. Otherwise, latest
guidance indicates breaking wave heights will largely stay 3-4
feet on Thursday, so no High Surf Advisory is planned at this
time.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
23/18z TAFs:
KCHS/KJZI/KSAV: Widespread MVFR cigs will prevail this
afternoon. The risk for extensive IFR cigs will increase after
00z, especially at KCHS. KJZI and KSAV may be just on the
eastern and southern periphery of the IFR cigs, but there is
enough data to support showing IFR cigs at both of those
terminals after 06z. Scattered showers may impact parts of the
Lowcountry by late Thursday morning with impacts more likely
after 18z. For now, a PROB30 for -SHRA with MVFR cigs was
introduced 15-18z at KCHS.

Extended Aviation Outlook: Gusty winds will persist into
Thursday, possibly Friday.

&&

.MARINE...
Through Friday: Marine conditions will continue to deteriorate
tonight into Thursday due to a tight pressure gradient between a
wedge of high pressure inland and deepening low pressure off
the mid- Atlantic coast. Small Craft Advisories are currently in
effect for all waters. Winds are expected to peak Thursday
afternoon into Thursday night when gusts to gale force (35 kt)
are likely over the offshore coastal waters 20-60 nm out. The
Gale Watches have been upgraded to Gale Warnings. Seas will peak
in the 6-11 ft range, highest offshore. Conditions will begin
to improve on Friday, but seas will be slower to subside and
will remain supportive of Advisories through the daytime hours.

Saturday through Monday: Outside of lingering 6+ ft seas over
the offshore GA waters on Saturday, no additional marine
concerns are expected the remainder of the weekend through
Monday.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...High Risk for Rip Currents from Thursday morning through Thursday
     evening for GAZ217-219-239-241.
SC...High Risk for Rip Currents from Thursday morning through Thursday
     evening for SCZ148>151.
     Coastal Flood Advisory until 8 PM EDT this evening for SCZ149-
     150.
MARINE...Small Craft Advisory from 6 AM to 11 PM EDT Thursday for
     AMZ340.
     Small Craft Advisory until 8 PM EDT Friday for AMZ360-362-364.
     Gale Warning from 6 AM Thursday to 6 AM EDT Friday for AMZ380-
     382.
     Small Craft Advisory until 2 PM EDT Thursday for AMZ384.
     Gale Warning from 2 PM Thursday to 6 AM EDT Friday for AMZ384.

&&

$$