FXUS62 KCHS 180657 AFDCHS
Area Forecast Discussion National Weather Service Charleston SC 257 AM EDT Sat Apr 18 2026
.WHAT HAS CHANGED...
Confidence has increased that record highs will be challenged again today. Additionally, details continue to come into focus for tomorrows cold front.
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.KEY MESSAGES...
- 1) Record-setting heat possible again today as dry weather
continues.
- 2) A cold front will bring low end rain chances Sunday,
followed by a brief cooldown early next week.
- 3) Minor coastal flooding possible along the South Carolina
coast with the evening high tides this weekend.
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.DISCUSSION...
KEY MESSAGE 1: Record-setting heat possible again today as dry weather continues.
H5 ridge axis passes overhead today as surface high pressure continues to ridge in from the south and east. Guidance has been consistent is showing temps very similar to yesterday with highs in the lower to mid 90s inland of the afternoon sea breeze. These will once again challenge daily records... see CLIMATE section for more.
Additionally, the latest Drought Monitor indicates D4/Exceptional Drought over a small portion of interior southeast GA, with a recent expansion of the D3/Extreme Drought to encompass much of the remaining area. These persistent, very dry conditions combined with RH values dipping into the mid-20s ahead of the sea breeze again this afternoon merit attention from a fire weather standpoint, though wind gusts coincident with these min RHs only reaching to around 15 mph preclude the need for any fire weather hazard products. Nonetheless, we encourage folks to exercise caution with any activity that may cause a spark.
KEY MESSAGE 2: A cold front will bring low end rain chances Sunday, followed by a brief cooldown early next week.
Near term guidance indicates that a cold front will sweep across SE GA/SC during the daylight hours Sunday. The cold air advection in the wake of the front is strong enough to result in cooling temperatures beginning during the early afternoon hours. Temperatures should peak just prior to the front in the low to mid 80s, during the mid-day hours.
High resolution guidance indicates that a solid line of showers and thunderstorms will reach the Southern Appalachians Saturday evening. Convection is expected to gradually wane in the lee of the Appalachians Saturday night. The showers activity will remain isolated to scattered as it reaches the forecast area after sunrise Sunday. Forecast soundings indicates a very dry layer below H7 with little to no SBCAPE. Unfortunately, the rainfall will generally remain unmeasurable, with some locations receiving 0.01" to 0.03". In fact, HREF indicates less than a 20% chance for rainfall exceeding 0.05" on Sunday.
Temperatures will cool Sunday night into Monday morning. Guidance indicates low temperatures Monday morning may range from the mid 40s inland to the low to mid 50s along the coast. High temperatures on Monday should favor values in the mid to upper 70s, which is near the normal high temperature. A secondary cold front may push across the area on Monday, with CAA and clear sky Monday night. Low temperatures on Tuesday should be comparable to Monday's values. Temperatures will then warm back into the 80s by Wednesday.
KEY MESSAGE 3: Minor coastal flooding possible along the South Carolina coast with the evening high tides this weekend.
The combination of the new moon (yesterday) and perigee (tomorrow) will bring elevated astronomical tidal ranges this weekend into early next week. Minor coastal flooding is possible with this evening's high tide along the South Carolina coast. Tide levels will be elevated again with the Sunday evening high tide, but the coastal flooding threat is uncertain and dependent on the timing of the cold frontal passage during the day and the direction of the post-frontal winds.
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.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
VFR across the region into Sunday. Light winds continue through the morning. The sea breeze crosses the terminals midday through early afternoon, with post sea breeze winds being stronger than the last few days with 15 to 20 kt gusts expected. Winds diminish again around sunset.
Extended Aviation Outlook: Gusty winds are possible Sunday afternoon and evening.
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.MARINE...
Light to moderate southerly winds prevail across the coastal waters today, with gusty winds developing nearshore this afternoon with the sea breeze. The gradient begins to tighten tonight as a cold front approaches from the west with 20 kt gusts becoming more frequent through the early morning hours Sunday.
A strong cold front is expected to sweep across the marine zones Sunday afternoon. Winds will veer from the NNE by Sunday evening, with gusts between 25-30 kts outside the Charleston Harbor. Seas are forecast to build from 2-3 ft on Sunday to 3-8 ft by dawn Monday. A portion of the marine zones may be highlighted with Small Craft Advisories to highlight the gusty winds and building wave heights. High pressure will return over the region on Monday, remaining into the mid-week. Conditions appear to remain less than Small Craft Advisory criteria.
Rip Currents: A Moderate Risk of rip currents remains in place for all beaches through Saturday due to the combination of 2-3 ft breakers, modest onshore flow, and increasing astronomical influences associated with lunar perigee/new moon. An elevated risk for rip currents is possible on Sunday and especially on Monday as a pinched gradient associated with a passing cold front supports a gusty northeast wind event along the Southeast Coast.
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.CLIMATE...
Record High Temperatures:
April 18: KCHS: 92/1967 KSAV: 93/1967
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.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None. SC...None. MARINE...None.
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CEB/NED