The state weather agency said temperatures topped 35 degrees Celsius in several places today, warning that similarly hot weather would "raise the danger of heatstroke" the next day.
The Fire and Disaster Management Agency said three people died from heatstroke last week while a total of 3,179 people were taken to hospital, rising from 2,473 a week earlier.
The mercury soared past 30 degrees Celsius last week with high humidity as the country's month-long rainy season was coming to an end.
Nearly half those needing hospital treatment were aged over 65.