“What is the best way to treat headaches caused due to excessive heat?”

Remain well hydrated and avoid alcohol and caffeine. Sports drinks help replace trace elements lost in sweat.

Two factors that can be contributing are dehydration and/or allergies. Dry heat is known to potentially irritate the sinuses and hence lead to the headache. One does not have to be drenching in sweat to still have enough sensible loss of fluid to lead to dehydration, which can trigger headaches. As such, plenty fluid intake and control of sinus inflammation/irritation would be two things to explore. Further work-up based on more detailed personal and past medical history, other medications that you are taking, other symptoms, etc.