Here to clear up any confusion on the daily summer "Blank is the hottest part of the US"

I'll start with my conclusion. The Houston down to McAllen/Brownsville to Laredo, in addition to Phoenix/Death Valley is the hottest part of the US. You might even be able to draw a line from Houston to Shreveport and include that as well to Houston to McAllen. Reason being is that it is the confluence of where the extreme high temps of the SouthWest meet the extreme high humidity of the Gulf SouthEast. Once you start getting further east from TX/LA border, the Gulf breeze begins to lower temperatures more. Despite the Houston area not receiving nearly the rainfall as Nola/Mobile, it is the most humid area of the US (SETX/SWLA). Houston getting up to 104 and 40% humidity, McAllen getting up to 108 to 110 with a 33-35% humidity put it at the 118 feels like in dead pan summer. As for Phoenix/DV, they are just simply hot as shite.

Most humid cities in the US
Most Humid cities in the US

It is also the hottest part of the entire Western Hemisphere. Equator has a more temperate climate that doesn't often get above 90 F, and I've yet to find anything in South America that competes with it after ample research. I've been researching this stuff every day of every summer for over a decade, and am here to debunk any myths about whatever is thought.

I'll start with Louisiana. South Louisiana gets a gulf breeze that usually doesn't ever get above 100, most times not above 97. It receives the same humidity as Houston (actually tiny bit lower). However, Houston gets to 104 in the dead summer due to the confluence of extreme temperatures of Texas/SouthWest, in addition to the humidity of the gulf. South East Texas to South Texas has it worst with this whole combination and confluence. In reality, Shreveport probably has higher heat index than South Louisiana, as North Louisiana has higher temperatures than SLA due to gulf influence. In any given day, if it's 97 in Lafayette, it's likely 101-102 in Shreveport. Shreveport averages just 2 percent below SLA in humidity but averages about 5+ degrees hotter in dead summer.

Florida is not anywhere close to the hottest part of the US. Florida and the eastern gulf gets more temperature moderation than the Western gulf. In dead summer in Gainesville, it is almost never seen to get to 100. Unlike Houston that will have 50+ of those days receiving slightly higher humidity than Gainesville. Gainesville usual high in dead pan summer will be 95-96.

Onto Phoenix, AZ. Arizona. Phoenix will get to 118 in the dead of summer. However, humidity will rarely eclipse 17% in these days, and most days will be around 14-15%. This basically means that the feels like and temp are going to be near the same.

Onto Death Valley, CA. I start by saying "YES EXTREME LOW HUMIDITY AND HIGH TEMPS CAN LEAD TO FEELS LIKE BELOW TEMP". Several days last summer I looked at Death Valley when it was around 123 deg F. The humidity was 4%. This led to a feels like of around 111. Humidity isn't always this low, but Phoenix is actually around 5% or so higher humidity than Death Valley from times I checked, but Death Valley has higher temps. It seemed to potentially be a washout in heat index btwn the 2.

Onto the more central deep South. Talking Southern AL, Southern GA, Panhandle Florida. Temps here don't often get above 97-ish due to gulf influence. They also have slightly lower humidity than SWLA/SE TX by about 3-4%. So between being on average, 6 or so degrees cooler than Houston, they also have a 3-4% lower humidity. Not in debate of close to being hottest places in the US.

I've been looking at this stuff daily in the summer for decades. After all this research I've done, the hottest part of the US is Houston to McAllen and Phoenix/Death Valley. If you want to stretch it even further, then you could maybe draw a straight line from Shreveport to Laredo/McAllen. Reason why it is this way is because it is the convergence of extreme high temps in the West and the extreme high humidities of the Gulf. Then you have the Phoenix area at 118 feels like and 118 actual temp.

The places like Phoenix and Death Valley as of right now are going to be hotter than the Brownsville all the way up to Lufkin area. Phoenix/Death Valley warms up much faster starting 110+ in early June. However, by late July, early August this is where they begin to be equal in feels like temp between there and Houston/McAllen.