You're correct, hottest place on earth that isn't a volcano or artificial is 56.7C, it's probably impossible without special circumstances (like a solar flare) to get that much hotter
I just find it funny that most of the comments here are about the temperature in TL's country rather than the chapter.
That being said, it was pretty fucking sweet to read though I'm pretty certain author is just drawing Hinomori with one hand because those are some pretty big melons. Makes the panic attack seem a little serious.
In late June or early July it'll probably hit 118 F here in Phoenix, AZ. In late July or August the temps will probably only get up to 110 or 112 F but there will actually be a little humidity then. Today (March 24) it's supposed to hit 95 F but the relative humidity is only 13% with a 31 F dew point. The highest temperature on record at Phoenix Sky Harbor Airport was 122 F on June 26, 1990. The highest temperature recorded in Arizona was 128 F on June 29, 1994 at Lake Havasu City. Even when bone dry those temperatures can be fatal with lack of hydration or when the only water available is well above body temperature.