As more people succumb to heatstroke in the sweltering summer, government agencies are calling on the public, especially children and the elderly, to keep the thermostat set below 28 degrees and drink plenty of water.

The Meteorological Agency expects this summer to be hotter than normal thanks to high pressure over the Pacific caused by above-average rainfall off the east coast of the Philippines. The number of people nationwide taken to receive medical treatment for heat-related illness between July 9 and Sunday surged 2.5-fold to 2,483 from 979 in the week before, according to the Fire and Disaster Management Agency.

On Sunday alone, the most recent day the agency has figures for, there were 827 such patients. However, the daily figures for Monday through Wednesday "must be far higher," said agency official Kazuya Watabe, citing higher temperatures. There were between 145 and 402 patients a day from July 9 to Saturday.

From July 9 to Sunday there were five heat-related deaths, compared with four from May 28 to July 8, the agency said.

According to the Meteorological Agency, there's a 40 percent chance that August and September will be hotter than average in east Japan. By the same token, chances are even that the summer will be just as hot as normal or cooler. In west Japan, August has a 40 percent chance of being hotter than normal, a 40 percent chance it will be the same as usual and a 20 percent chance of being cooler. The corresponding figures for September are 40, 30 and 30 percent, according to the agency.

Both agencies are calling on members of the public to drink water even when they are not thirsty, to rest often, eat healthily and call an ambulance when they lack strength to drink water, feel deeply fatigued and have difficulty moving.