I have taken a reading, in controlled conditions (in the shade of a berm next to an earthen road, digital thermometer accurate to +-0.1C), of 54.2C - admittedly

I have taken a reading, in controlled conditions (in the shade of a berm next to an earthen road, digital thermometer accurate to +-0.1C), of 54.2C - admittedly over dust rather than vegetation, but there was no vegetation. I’d been collecting all sorts of data along our route (started from the U.K.), mostly just for the sake of it. This was in the Kazakh steppes, in 2012, about 100km NW of Aralsk - it was under 20% rh, and the heat was just unbearable - it took us tens of litres of water each per day to replenish sweat, just sitting on our asses in a car with no a/c. The dashboard melted. The glue in the headliner melted, and dripped down the walls. The grip on the steering wheel sloughed off, and the gear shift head glue melted, and that fell off too. At the end of the day, we had an uncomfortably hot shower with the remaining water that had been sat in the car with us. 54C, when measured as an accurate temperature, manifested as 60C on the thermometer in the car, which was its maximum, as it had shown that for several days before the LCD also melted. So yes, take the apocryphal tales of high temperatures with a big pinch of salt, as most will be overreported, but I can vouch that this particular temperature isn’t entirely unprecedented on Earth - what is worrying is that it is now frequent enough that it is being observed, rather than just being a random nutter in the dust with a penchant for data.