FXUS62 KCHS 272357 AFDCHS
Area Forecast Discussion National Weather Service Charleston SC 757 PM EDT Sat Jun 27 2026
.WHAT HAS CHANGED...
KEY MESSAGE 1 was updated for ongoing trends. The Aviation Section was updated for the 00Z TAF issuance. The Marine Section was updated for ongoing trends.
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.KEY MESSAGES...
- 1) Hot and humid conditions will occur this weekend and into
Monday, with Sunday temperatures near 100 degrees in some locations. Heat Advisories could be needed on Sunday.
- 2) Temperatures will decrease to near normal for the middle of
next week, then the heat returns for the end of next week. Rainfall chances gradually decrease throughout next week.
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.DISCUSSION...
KEY MESSAGE 1: Hot and humid conditions will occur this weekend and into Monday, with Sunday temperatures near 100 degrees in some locations. Heat Advisories could be needed on Sunday.
Tonight: Overnight lows will challenge record high minimums at some of the local climate sites, only dropping into the 70s. This will provide little relief from the heat heading into Sunday, which is forecast to be the warmer of the days this weekend.
Sunday: The only synoptic change is a slight shift in the surface high pressure while ridging holds aloft, which will yield a more westerly surface wind across the local area. This will likely keep the sea breeze pinned along the coastline until later in the afternoon allowing temperatures to warm into the upper 90s and maybe even touch 100 in a few spots. A pinned sea breeze will allow lower the chances of afternoon convection, with only isolated coverage anticipated. Given the humid airmass in place along with the warm temperatures, heat index values will likely reach to 100-105 west of I-95 and 105-110 along the coastal corridor. At this juncture a Heat Advisory has not been issued for the coastal counties as confidence is too low that criteria (>108 heat index values) will be reached for 2 hours or more. The need for a Heat Advisory will be reevaluated with future forecast updates.
Monday: The ridging aloft will persist into Monday while at the surface a weak front will stall off the southeast coastline. Another hot day is forecast, with temperatures reaching into the mid 90s once again. Combined with dewpoints in the 70s heat index values will be in the 103-110 range. With the stalled front off the southeast coast an increase in shower/thunderstorm coverage is anticipated, with the forecast featuring scattered to widespread PoPs in the afternoon. Given the higher coverage of convection a Heat Advisory is unlikely, as the showers/thunderstorms will inhibit temperatures from reaching their full potential. While widespread severe weather is not anticipated, strong to marginally severe storms are possible especially along boundary interactions.
KEY MESSAGE 2: Temperatures will decrease to near normal for the middle of next week, then the heat returns for the end of next week. Rainfall chances gradually decrease throughout next week.
Ridging aloft will remain the dominant synoptic feature next week. Initially centered over the TN Valley early in the week and then shifting eastward towards the East Coast by the end of the week. Temperatures are forecast to moderate to near normal values in the middle of the week before warming to above normal as the ridge shifts eastward towards the end of the week. High temperatures could again reach into the mid to upper 90s, which combined with dewpoint values in the 70s will likely yield heat index values in the 100-110 range. Heat Advisories could be required for portions of the forecast area at the end of the week and into the holiday weekend.
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.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
Other than a brief shower possibly impacting the CHS terminal early this evening (through 01Z), expect VFR conditions to generally prevail at CHS/JZI/SAV terminals through 00Z Monday. A few thunderstorms could approach the CHS/JZI terminals from the northwest mid-late afternoon into early evening Sunday, with confidence slightly higher in impacting the CHS terminal. A PROB30 group for 5SM/-TSRA has been introduced at CHS between 20-24Z Sunday as a result.
Extended Aviation Outlook: Showers and thunderstorms may lead to flight restrictions, especially from late Sunday afternoon into Sunday night as a front moves toward the area. Some flight restrictions are possible due to these storms. Brief restrictions are also possible due to convection Monday and Tuesday afternoons.
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.MARINE...
Through Tonight: A typical summertime pattern will persist across the marine waters. South/southwest winds will remain elevated along the coastline overnight, with gusts generally in the 15-20 kt range, although gusts could be few kt higher into early evening. Seas will range between 2-4 ft.
Sunday: Surface High pressure over the Atlantic will cause backing of the winds during the afternoon. The highest winds will be along the land/sea interface with the formation of the sea breeze. Gusts to 20 or briefly 25 kt will be possible, especially as the sea breeze crosses through the Charleston Harbor. At night, winds will veer and gradually ease.
Monday through Wednesday: Expect weak winds on Monday as a prefrontal trough moves into our area. Winds then shift to the NE by early Tuesday, where they'll prevail into Wednesday.
Rip Currents: Gusty winds with the afternoon sea breeze and a 2-3 ft swell at 8-9 seconds will generate a Moderate Risk of rip currents at all of our beaches this weekend.
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.CLIMATE...
Record High Temperatures:
June 28: KCHS: 99/1998 KSAV: 100/1998
July 3: KCHS: 98/2019
Record High Minimum Temperatures:
June 27: KCHS: 77/2015
June 28: KCHS: 78/2013 KCXM: 81/1998
June 29: KCHS: 79/1977
July 1: KCHS: 77/2024
July 3: KCHS: 78/2016
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.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None. SC...None. MARINE...None.
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