The Messenger of Allah said: "When it is very hot, then wait for it to cool down before you pray, for intense heat is from the flaring up of the Hell-fire."
أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ إِذَا اشْتَدَّ الْحَرُّ فَأَبْرِدُوا بِالظُّهْرِ فَإِنَّ شِدَّةَ الْحَرِّ مِنْ فَيْحِ جَهَنَّمَ