Now that you won the cold-endurance contest, Rahdo on Mount Granajh challenges you to endure the heat.
Quest Location
After you complete Cold-Endurance Contest!, talk to Rahdo on the peak of Mount Granajh to start the quest.
How to Complete the Quest
You can easily complete this quest by fusing a sapphire to a weapon and equipping that weapon. The weapon will keep you cool for the entire duration of the contest. When you have equipped your sapphire-fused weapon, talk to Rahdo to pay 150 rupees to start the contest, then stay on top of the pillar until you win.
Quest Reward
Rahdo gives you 300 rupees.