FXUS62 KCHS 261025 AFDCHS
Area Forecast Discussion National Weather Service Charleston SC 625 AM EDT Sat Jul 26 2025
.SYNOPSIS...
Atlantic high pressure will prevail through early next week, while a trough of low pressure resides inland.
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.NEAR TERM /THROUGH TONIGHT/...
Today: Strong upper level ridging noted by a H5 596 dam will become centered over the forecast area today. Additionally, surface high pressure will lie across the Florida Peninsula, with an inland trough developing throughout the day. Strong subsidence and mid-level dry air seen in model soundings will limit convection potential. In fact, model consensus shows no signs of shower/thunderstorm development today. Therefore, we are forecasting no mentionable POPs along with mostly sunny skies and the development of a few shallow cumulus clouds. The main concern today will be the heat as highs reach the upper 90s with some locations approaching the 100 degree mark. The Charleston Intl. climate site (KCHS) is even expected to near record high temperatures (see Climate section below). Additionally, the combination of hot temperatures and dew points in the 70s will result in heat indices ranging 108-112 degrees across southeast South Carolina and southeast Georgia. Heat Advisories have been issued for the entire forecast area.
Tonight: Conditions will remain quiet overnight with no convection expected. Minimum temperatures will only fall into the upper 70s for most places and lower 80s along the beaches and Downtown Charleston. The Heat Advisory will continue through tonight given the lack of relief from the warm overnight temperatures.
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.SHORT TERM /SUNDAY THROUGH MONDAY/...
Main forecast concern early next week continues to be the prolonged heat event. Extreme Heat Watches are currently in place for Sunday and Monday.
Anomalously strong ridge will dominate the upper level pattern Sunday through Tuesday, with its center initially overhead then gradually shifting/expanding westward. At the surface, high pressure will sit offshore while a trough resides inland.
The hottest days of the upcoming week are set for Sunday and Monday, when near record highs are forecast (see climate section below). Many spots away from the immediate coast could reach or exceed 100F. Heat indices will be even higher, possibly exceeding Extreme Heat Warning criteria of 113F. Have maintained the current Extreme Heat Watch for the entire area for Sunday and Monday. It will not be quite as hot on Tuesday, but still toasty. Additional heat headlines are possible with heat indices potentially reaching Heat Advisory criteria of 108F. Little relief is expected overnight with lows only in the upper 70s to around 80.
Large scale subsidence should keep convection to a minimum on Sunday with the forecast currently indicating dry conditions (PoPs < 15%). Rain chances return for Monday and Tuesday as models indicate shortwave energy dropping across the region on the eastern periphery of the ridge.
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.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
The forecast area will remain under the influence of an expansive upper ridge centered over the south central U.S. through the middle of next week, before a larger scale trough moves into the northeastern U.S. during the latter half of the week. Some Heat Advisory concerns (heat indices of 108 or greater) continue through Wednesday, and potentially Thursday, but overall signals point to improvement from the heat wave. A front could approach the region late in the period. Daily showers and thunderstorms are forecast.
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.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
26/12z TAF: VFR through Saturday night.
Extended Aviation Forecast: Prevailing VFR. Brief flight restrictions are possible in afternoon showers/thunderstorms next week.
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.MARINE...
Today and Tonight: South to southwest winds around 10 kt or less will prevail. Seas will range 2-3 ft, decreasing to around 1-2 ft late tonight.
Sunday through Thursday: No marine concerns are anticipated through the middle of next week. Generally expect southerly flow with speeds less than 15 knots. Seas will average 1-3 feet.
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.CLIMATE...
Record High Temperatures:
July 26: KCHS: 99/2010
July 27: KCHS: 100/2005 KSAV: 100/2010
July 28: KCHS: 101/1949 KSAV: 102/1949
Record High Minimum Temperatures:
July 26: KCHS: 78/2012
July 27: KCHS: 80/2014 KCXM: 84/2021 KSAV: 80/1885
July 28: KCHS: 80/2016 KCXM: 83/1999 KSAV: 81/1878
July 29: KCHS: 80/2016
July 30: KCHS: 81/2016 KCXM: 83/2016 KSAV: 81/1878
July 31: KCHS: 80/2022 KSAV: 80/2010
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.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Heat Advisory from 10 AM this morning to 10 AM EDT Sunday for
GAZ087-088-099>101-114>119-137>141. Extreme Heat Watch from Sunday morning through Monday evening for GAZ087-088-099>101-114>119-137>141.
SC...Heat Advisory from 10 AM this morning to 10 AM EDT Sunday for
SCZ040-042. Extreme Heat Watch from Sunday morning through Monday evening for SCZ040-042>045-047>052. Heat Advisory until 10 AM EDT Sunday for SCZ043>045-047>052.
MARINE...None.
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NEAR TERM...BRS SHORT TERM...ETM LONG TERM...ETM AVIATION...BRS/ETM MARINE...BRS/ETM