The hottest weather on Earth is something of an unknown. Temperatures can only be measured in places that have thermometers, and thermometers are not everywhere. The hottest temperature recorded and accepted as valid by the meteorological community is the 134 degrees in Death Valley, California, recorded July 10, 1913. However, that record is under suspicion as none of the nearby weather stations recorded extraordinarily hot weather on that day. If the record is disallowed, the world record will become 130 degrees, also recorded at Death Valley.
The Death Valley weather station is located in a notoriously hot spot on Earth, but it might not be the hottest. A few locations in Ethiopia and Iran are likely about as hot and may well have been hotter than Death Valley. But these locations do not have calibrated weather measuring stations.