Charleston Weather Blog

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

The week ahead: Turning hot again

/ June 19, 2022 at 4:57 PM

All good things must come to an end, and that includes our brief respite of below-normal temperatures that we’ve seen today. We do get one more crisp (by June standards) morning with lows bottoming out in the low 60s away from the immediate coast Monday morning. This will be followed by highs rising to around 90° in the afternoon. Thankfully, humidity will stay on the lower side to start the week as drier air remains firmly in place. Northwest flow around an anomalously strong ridge of high pressure will act to further dry out the atmosphere during the day, which will also help temperatures out to the mid-90s on Tuesday and the upper 90s on Wednesday thanks to compressional heating from downslope flow. The tempering of humidity will help keep heat indices from getting too far out of whack, but at the end of the day, the mid-to-upper 90s is still pretty hot weather. The lack of moisture will suppress development of afternoon showers and thunderstorms, so we look to stay rain-free through Wednesday.

We’ll start to see changes on Thursday as the aforementioned ridge of high pressure shifts west a bit. This combined with a little bit more troughiness and onshore flow at the surface will help reintroduce some slight shower and thunderstorm chances for Thursday and Friday afternoons. A front encroaching on the area could lead to a little uptick in storm chances for next weekend, but so far it doesn’t look like anything completely out of the ordinary for mid-to-late June.

A great Sunday to get out and about with dad

/ June 18, 2022 at 9:18 PM

Folks, we’ve been handed a gift: A very not-humid, spring-ish mid-June day for Father’s Day. We start the day with lows in the mid-60s away from the coastline under mostly clear skies. Temperatures will warm into the mid-80s in the afternoon while dewpoints mix out into the 50s — very rare air for this point in the year around here. This will yield relative humidity values below 40%, and as such, a wonderful Father’s Day gift from Mother Nature. We’ll have a few clouds from time to time, so make sure you’re using sunscreen, but other than that, there are no weather concerns. Enjoy!

Saturday’s still hot, but not as humid

/ at 7:38 AM

Another hot day lies ahead as air temperatures head back up to the mid-90s thanks to downslope flow from the Appalachians. Said downsloping, though, will help keep dewpoints — and the heat index — from getting too far out of bounds. Heat indices will “only” peak around 100° this afternoon. While still quite hot, we aren’t headed into that more dangerous temperature territory today as a result of the drier air. This will also essentially suppress thunderstorm development; in fact, today marks the beginning of what looks to be a rain-free few days across the area. With just a few clouds expected, definitely deploy the sunscreen as the UV index approaches 11 during the peak of the day.

Friday & the weekend: Strong storms possible, then a little less humidity

/ June 16, 2022 at 5:23 PM

We have another potentially boy-band-hot (98°) day on tap for Friday as temperatures soar ahead of a cold front. Expect heat indices to once again approach 110°, with a heat advisory a near-certainty as a result. Said heat and humidity will translate to plenty of thunderstorm fuel for potential strong to severe thunderstorms in the evening hours ahead of the front. There’s still model disagreement about exactly when and where thunderstorms will fire, but if and when they do, a few will be capable of damaging wind gusts. You’ll want the weather radio nearby tomorrow evening, especially if you are out and about.

The front gets through late Friday into early Saturday, shutting off rain chances and even helping to dehumidify us a touch. Saturday will still be hot, with air temperatures reaching the mid-90s, but dewpoints in the upper 60s as opposed to the mid-70s will keep heat indices generally below 100°. Sunday looks even better — honestly a pretty fantastic day to get outdoors, particularly in mid-June — with a punch of cooler and drier air keeping air temperatures to the mid-80s for much of the area. The respite will be short-lived, though, as temperatures soar once again by the middle of next week, possibly flirting with 100° on Wednesday.

Thursday: Not quite as hot, but the respite is brief

/ June 15, 2022 at 9:46 PM

Thursday will run a little cooler — 91° with a heat index of 94° certainly qualifies — as onshore flow behind a backdoor cold front gives us a little break before the heat picks back up on Friday. With the slightly cooler weather comes a somewhat more stable atmosphere, which will keep the risk for afternoon showers and thunderstorms to a bare minimum. All in all, should be a fairly decent day for an outdoor dinner. (Might still be a bit much for eating lunch outside, though.)

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Rest of the work week: Staying hot

/ June 14, 2022 at 10:39 PM

The rest of the work week will remain hot — though not to the degree that we observed today, with the first 98° reading at the airport since August of 2019 — with only a slight chance of a thunderstorm as a strong ridge remains firmly in place across the area. Heat indices could once again reach advisory criteria tomorrow with only a slight chance of a thunderstorm to cool things off. So it will go Thursday and Friday, too, though onshore flow behind a backdoor front will keep temperatures a little “cooler” on Thursday, topping out “only” in the low 90s. Bottom line: Stay geared up for hot weather for the foreseeable future. We’ve got a little break coming Sunday, but the heat will then just surge right back as we get into next week. (Such is summer.)

Coastal flooding will continue to be an issue with the evening high tides through Friday. Onshore flow should send tidal departures even higher on Wednesday evening, with moderate flooding expected with the 9:55 PM high tide. Expect scattered to potentially numerous road closures in downtown Charleston tomorrow evening as a result, though thankfully after the commute.

Hottest day so far in 2022 coming for Tuesday; a strong storm or two is possible, too

/ June 13, 2022 at 7:55 PM

Another dangerously hot day for the Lowcountry is on tap for Tuesday, as temperatures soar into the upper 90s — and perhaps over 100° well inland — in the afternoon courtesy of an anomalously strong ridge of high pressure aloft. Factor in the humidity, and it’ll feel as hot as 110°+ during the peak of the afternoon, prompting a Heat Advisory from 11am to 7pm for the entire Tri-County area.

We haven’t seen heat like this in a long while. The last time air temperatures reached Tuesday’s forecast high of 98°, COVID wasn’t even in our vocabulary: it was August 10, 2019.

Looking for thunderstorms to help temper the heat? Don’t count on them, as coverage should be isolated at best. If storms do get going, they’ll be able to take off and become severe with damaging wind gusts and large hail. We’ll also be watching areas to our north with close interest tonight into tomorrow, as a potential mesoscale convective system could move into and through the Mid-Atlantic states during the day. This could help drive a cold front southward, bringing with it perhaps a better shot at some showers and storms later in the evening. These, too, could be on the strong side. The Storm Prediction Center outlines the area in a marginal (1 out of 5) risk for severe storms Tuesday.

Oppressive heat looks to continue for much of the rest of the week, with a slight downshift in intensity Thursday and Friday (but not enough to elude more Heat Advisories). Mercifully, this heat wave should break on Sunday after another front pushes through the area and actually cools things off somewhat. But for now, make sure you’re getting plenty of shade and water if you must be outside in the afternoon.

Coastal flooding will continue to be an issue as well around the times of evening high tide. Watch for the potential for road closures each evening, and be on the lookout for Coastal Flood Advisories from the National Weather Service.

The week ahead: Here comes a heat wave

/ June 12, 2022 at 5:00 PM

The hottest weather thus far in 2022 will arrive this week as a strong ridge of high pressure builds over the Southeast. The heat wave will peak Tuesday and Wednesday, with highs in the upper 90s expected and heat indices likely exceeding 110° both days. We stay hot heading into the weekend before a frontal system looks to push through Saturday night, leaving us with slightly cooler temperatures — if you could call 90° “cooler” — for Sunday.

Compounding things, low temperatures will struggle down to the mid-70s on the coolest mornings. There may be some mornings near the coast where temperatures don’t drop below 80°. The heat during the day with the lack of cooling at night will make for an oppressive few days. Check on your neighbors, especially those with vulnerability to the heat, during this tough stretch. Make sure you’re getting plenty of water and taking frequent shady breaks if you’ve got to be outside during the peak of the afternoon.

Thunderstorms will be few and far between for much of the week, with the better rain chances likely overnight Saturday into early Sunday morning with the frontal passage. Even then, right now the rain probabilities are in the 20-30% range.

Finally, astronomical factors and favorable winds will combine for minor to moderate tidal flooding with each evening’s high tide. Be ready for road closures in a few spots in downtown Charleston at times this week, and keep an ear out for Coastal Flood Advisories from the National Weather Service.

Friday & the weekend: Pretty warm, turning a little stormy for Saturday

/ June 9, 2022 at 6:51 PM

Friday and the weekend will remain on the warm side, with the best chance at showers and thunderstorms coming on Saturday before tapering off on Sunday.

We’ll be the beneficiary of some drier air on Friday, which should help keep thunderstorms to a minimum and put a little governor on the humidity. This will be short-lived, though, as the front that helps to usher in this drier air lifts back north of the area, putting us back in the soup on Saturday. It looks like showers and thunderstorms will begin to break out by mid-morning and continue well into the evening hours. Exact placement of storms will be driven by where storms initially fire and the subsequent propagation of outflow boundaries and the seabreeze. The trough driving some of this unsettled weather begins to lift north on Sunday, leaving us with generally standard chances of thunderstorms on the seabreeze in the afternoon.

Overall, expect highs around 90° each day ahead of thunderstorms, with heat indices generally in the mid-90s. This’ll feel cool compared to what’s coming down the pike for next week — it looks like we might have a few days of near-heat advisory conditions (heat indices 105°+) with little in the way of storms to help cool things off at least temporarily. We’ll want to watch trends closely for this potentially sweltering heat!

Hot day Thursday, but a little drier air over the weekend keeps heat indices in check

/ June 8, 2022 at 6:51 PM

Despite the air temperature topping out around 91°, Thursday’s going to be the hottest day of the week because of quite a bit of humidity. Heat indices could approach 100° in the afternoon before scattered thunderstorms develop along the inland-moving seabreeze. A storm or two could be on the strong side where outflow boundaries intersect, but as is typical in the summertime, any severe weather will be quite localized. Heat will certainly affect everyone, though, so be sure that you’re getting plenty of water and shade if you’re outdoors in the height of the afternoon.

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