After reaching 99° again on Tuesday, we will start to see a a slow down-trend — though not necessarily an end — to the heat wave as we get through the second half of the work week and head toward the weekend.

Another extremely hot day is on tap for Tuesday as temperatures take what should be one last shot at the 100° mark before sanity begins a slow return to the forecast. We’ll start the day near 80° inland of the coast, and we’re almost assuredly not getting below 80° at the coast and in downtown Charleston. From there, temperatures will soar into the upper 90s to near 100°, with the best risk of reaching the 100° mark inland of Highway 17. And then there are the dewpoints running in the mid-to-upper 70s, which will propel heat indices well into the mid-110s for many of us, with a few readings getting uncomfortably close to 120° in more rural spots. For the first time in this heat wave, an Extreme Heat Warning is in effect for the entire Tri-County, including Dorchester; to this point, we’ve only seen those warnings come out for Berkeley and Charleston. Continue to heed precautions for extreme heat: air conditioning if at all possible, but frequent breaks in the shade with water if you must be outdoors.

There will be a slightly better chance of thunderstorms Tuesday afternoon than we saw on Monday, which will cool some of us off. The price for this, though, is an elevated risk for strong and potentially damaging wind gusts, excessive lightning, and very heavy — perhaps flooding — rain in a few spots. Instability will be running on the high end of what we usually see around these parts, so any storm that can take advantage could take off like a rocket. The good news is that without much shear, storms will generally pop, rain for a while, and then collapse.

The weather story for the rest of the work week will be the intensifying heat wave across the area as high pressure building in aloft continues to strengthen, while southwesterly winds continue to pump in high-dewpoint air that will send heat indices over 110° in spots.

It’s a very toasty start to the school year for Charleston County on Tuesday as this week’s heat wave will begin in earnest as high pressure aloft takes hold. We’ll start the day on a very mild note, with lows in the mid-to-upper 70s warming to the mid-90s in the afternoon. Dewpoints will run in the low-to-mid-70s inland, while closer to the coast, they’ll run in the upper 70s. That will help drive heat indices solidly into the 100s, with the highest heat indices expected in the Highway 17 corridor and points east. A Heat Advisory will be in effect for Charleston County and the southern part of Berkeley County from 11am-8pm, when heat indices should exceed 108° and could top out near 111° as the seabreeze pushes by. The aforementioned high pressure will make it much harder for thunderstorms to develop, though a couple popup showers will be possible. With that in mind, though, don’t count on thunderstorms to impart any relief from the heat.

Another hot and humid day awaits for Wednesday, then a bit of drier air filters in to take the edge off the heat ever so slightly to close out the work week and the month of July.

The weather story this week thus far has been the extremely warm and muggy mornings. This morning was no exception — downtown has, thus far, only dropped to 84° while the airport’s low is 80°. If these lows hold, they would break the record warm low temperature downtown and tie it at the airport. These warm lows will continue for the rest of the work week, which will not allow much relief from the mid-90s heat during the day.

Tuesday looks similar to Monday, with temperatures warming into the low-to-mid-90s in the afternoon after another sultry start in the upper 70s to low 80s. Heat indices inland will run in the low 100s, but may push 108° as we get closer to the coast and the higher-dewpoint air. Southerly winds will continue to be breezy, with gusts pushing 30 MPH at times midday.

The pattern turns a little more settled as high pressure builds back in aloft. As a result, we will see more sunshine as the week progresses, though with that will come warmer temperatures, too, which could push Heat Advisory thresholds in spots.

Showers and thunderstorms will feature prominently in the forecast on Tuesday as they develop around a stalled boundary lingering to the south. Periods of heavy rain will be possible, and an area or two of freshwater flooding can’t be totally ruled out. However, severe weather is unlikely, and this will largely be a beneficial rainfall event. Even better, highs should peak below 90° for the first time since June 24. So, even though there will be rain, it’ll be awfully nice to not be baking.

The main flooding concern arrives with the evening high tide; minor to moderate coastal flooding will be possible between 7-10 PM. We’ll need to monitor where the rain is carefully; any rain that coincides will cause issues downtown.

Dangerous heat and humidity continues across the Lowcountry as we get into the second half of the work week with fewer opportunities for relief from thunderstorms.