Charleston Weather Blog

Forecast explanations, atmospheric science, and other cool weather-related stuff for Charleston, SC

Friday & the weekend: Heavy rain expected, Flood Watch through Sunday morning

/ August 21, 2025 at 10:47 PM

Friday and the weekend will be on the unsettled side as a front stalls out nearby. Waves of low pressure developing along the front will help to tap into resurgent tropical moisture, and given how soggy it’s been this month, it won’t take terribly much for flooding to develop. Thus, a Flood Watch will go into effect at 8am Friday, lasting into late Saturday night/early Sunday morning. We’ll want to pay close attention around the evening high tides on Friday and Saturday, as water levels in Charleston Harbor will remain elevated in the wake of Hurricane Erin. Salt water flooding looks like a good bet, and any heavy rain on top of that would cause widespread issues in downtown Charleston. Keep an ear out for flood alerts from the National Weather Service, especially for Flash Flood Warnings, as they may become necessary over the next few days.

The upside to this is that temperatures will run below normal. Highs on Friday should only top out in the mid-80s, while Saturday’s high may only climb to the low 80s. We’ll warm up a little on Sunday as the periods of heavy rain should taper off, but highs in the mid-80s still run a few clicks below the normal high of 89° this time of year.

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Thursday: Another warm day, but changes are afoot

/ August 20, 2025 at 10:22 PM

Thursday will be another warm day across the Lowcountry, with lows in the mid-70s warming to the low-to-mid-90s in the afternoon. Heat indices will run in the upper 90s to perhaps 100° in spots under generally partly cloudy skies. We should start to see cloud cover begin to thicken a bit as we get into the afternoon and evening hours, though, with rain chances increasing as Hurricane Erin accelerates to the northeast and a cold front drives south into the area, stalling out as it gets to our south.

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Rest of the work week: Erin’s coastal impacts peak; more unsettled toward the weekend

/ August 19, 2025 at 10:37 PM

The main story for the next couple days will be Hurricane Erin’s impacts on the Lowcountry. While not a direct hit — the storm will pass hundreds of miles offshore — the strong, dangerous rip currents and high surf will cause beach erosion and coastal flooding issues over the next few days.

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