Charleston Weather Blog

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

Tuesday: Another warm day, but a little relief is inbound

/ August 21, 2023 at 10:35 PM

Tuesday will be another rather warm day across the Lowcountry. After we topped out at 95° on Monday, temperatures should head a little higher on Tuesday, back into the mid-90s once again under partly cloudy skies. Peak heat indices will range from near 105° inland to around 108° closer to the coast where the higher-dewpoint air will be found. This is in the range where heat illness becomes an escalated concern, so be sure to take the normal heat precautions if you’re out and about Tuesday afternoon. Showers and thunderstorms are unlikely given ridging aloft, but a stray shower can never be totally ruled out.

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The week ahead: Quiet and warm as high pressure dominates

/ August 20, 2023 at 10:32 PM

We have a generally quiet week on tap as high pressure is the dominant weather player across the central and eastern US. It’s going to be warm, especially to start the week as dewpoints in the low-to-mid-70s combine with air temperatures in the mid-90s to yield heat indices around 102° on Monday and 105°+ on Tuesday under partly cloudy skies. A front might allow for a couple storms Wednesday before quiet weather resumes to close out the work week. It’ll be a little “cooler” and drier behind the front — dewpoints in the upper 60s to around 70° and air temperatures in the low 90s will still run above normal, but heat indices should remain in check as drier air mixes down and limits cloud cover. Isolated storm chances return Saturday afternoon, with a better chance of storms on Sunday as another front approaches the area.

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Sunday’s forecast: Warm and muggy with a few storms

/ August 19, 2023 at 9:57 PM

Sunday’s forecast looks fairly similar to Saturday’s: We’ll start the day in the mid-70s and head toward around 90° in the afternoon under partly cloudy skies. Heat indices will top out around 100-101°, with perhaps locally higher values closer to the coast. A scattering of showers and thunderstorms will once again be possible as the seabreeze presses inland, with heavy rain a continued concern with decent low-level moisture still in place. Ridging developing aloft will keep a lid on widespread coverage of showers and storms.

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Weekend forecast: Warm and muggy with scattered afternoon storms

/ August 18, 2023 at 9:42 PM

The weather this weekend looks fairly August-like — lows in the mid-70s, highs in the low 90s, with a chance for thunderstorms each afternoon, but no rainouts, either.

Moisture begins to return to the area Saturday as a front approaches and stalls out nearby. The front won’t be a huge contributor to storm chances, it looks like, with the seabreeze doing a bulk of the dirty work in the afternoon and evening hours. The moisture isn’t very deep, though, and that should limit storms to generally isolated to scattered coverage. Highs top out in the low-to-mid-90s; combine this with dewpoints heading into the low 70s, we should see heat indices around 100° for a time.

Trajectories turn more onshore for Sunday, which will act to keep a chance for scattered showers and storms in the forecast for much of the day, progressing inland with time. Widespread coverage isn’t expected, though, and it won’t rain all day at any one location. Highs top out in the low 90s with heat indices around 100-101°.

This might be the last real rain we see for a few days as an expansive ridge builds in across the area for the upcoming work week (and first week of school), which may send heat indices back over 105° across the area for a good chunk of each afternoon. It remains to be seen if heat advisory-level conditions return — stay tuned.

Friday & the weekend: Break from storms Friday, scattered storms over the weekend

/ at 7:01 PM

Drier air moves into the area for Friday, yielding mostly sunny skies and a rain-free day. We start the day in the mid-70s before highs head to the mid-90s in the afternoon. Drier air mixing down from aloft will temper dewpoints somewhat, and this will help to keep heat indices from getting too far out of hand. Still, feels-like temperatures will top out in the mid-to-upper 90s. So, while it’s not going to be cool outside, it’s also not going to feel like it’s 110°. (Take the wins where you can get them.)

Scattered storms head back into the forecast starting Saturday afternoon as a front stalls out nearby and waves of low pressure move along it. Surface dewpoints will head back into the mid-70s, and this will yield heat indices over 100° Saturday afternoon before storms fire. Still, coverage should be scattered at most with ridging aloft creating a bit of capping.

Sunday will run a tad cooler (air temperature-wise, anyway) as surface winds turn more onshore. Expect highs in the upper 80s to around 90° in the afternoon, but heat indices will run around 100°. Scattered showers and some thunderstorms will be embedded within this onshore flow, and will be coming ashore from time to time, but by no means is it a washout as coverage should once again generally be in the scattered category. So, while it’s not the perfect setup for the last weekend before school starts, it won’t be the worst you’ve ever seen, either.