Experts have warned that temperatures of 50 degrees Celsius could become an annual occurrence in Saudi Arabia by the end of the century.
As protection from the heat, many pilgrims have been walking with umbrellas to shield themselves from the sun, while others carry their folded prayer blankets above their heads.
One security guard was seen fanning a seated pilgrim, apparently overcome by the heat at Mina. According to official figures, at least 287 people have been treated for heat exhaustion and heatstroke.