India, April 29 -- While summers in north India normally build gradually, allowing the human body to adjust over weeks, the transition to extreme heat has been abrupt this year, leaving little room for biological adaptation and putting people at higher risk of heat-related illnesses, warned experts.

"High temperatures arriving earlier than usual put a strain on the body's ability to acclimatise to hot weather, a phenomenon called seasonal or heat acclimatisation," said Dr Mugdha Tapdiya, director of internal medicine at Fortis Hospital, Vasant Kunj.

Under normal conditions, repeated exposure to heat over days or weeks triggers a series of physical responses: the body begins to sweat earlier and more efficiently, heart rate under heat st...