Tokyo: Japan's weather agency on Sunday issued heatstroke alerts in 19 prefectures, including this season's first for central Tokyo and Kanagawa, as dangerously high temperatures gripped much of the country.

The Japan Meteorological Agency (JMA) said a high-pressure system is likely to cover western Japan and elsewhere, bringing mostly sunny and hot weather on Sunday.

Daytime highs in the mid-to high-30s were logged nationwide, including 38.3 degrees Celsius in Kuwana, Mie Prefecture, 37.9 degrees Celsius in Toyota, Aichi Prefecture, and 37.7 degrees Celsius in Tajimi, Gifu Prefecture, Hamamatsu, Shizuoka Prefecture and Kofu, Yamanashi Prefecture, the JMA said.

Weather officials advised people to use air conditioners as needed, take liquids and salt, and rest frequently when working outside, reported Xinhua news agency.

According to the Tokyo Fire Department, as of 3 p.m. local time on Sunday, 28 people aged between 9 and 89 in the capital had been taken to the hospital by ambulance for suspected symptoms of heatstroke.

The JMA said dangerously hot weather is also expected on Monday, urging people to continue to take thorough measures to prevent heatstroke.

Japan experienced its hottest June ever since record-keeping began in 1898, with the average monthly temperature being 2.34 degrees Celsius higher than the standard value, according to JMA data.

This is the first alert of the season issued for Tokyo and Kanagawa, the local news agency reported.

People are advised to use air conditioners as needed, take liquids and salt and rest frequently when working outside.

Meanwhile, atmospheric conditions are likely to become unstable, especially along mountains in western and eastern Japan, due partly to rising temperatures and damp air. Weather officials say localised downpours with thunder may fall, and are also calling for caution against lightning strikes, gusty winds and hail, the agency added.

Global warming has pushed up atmospheric air temperatures across the globe, another local news agency says, noting that the Pacific high-pressure system extending more strongly toward Japan and prevailing westerly winds meandering further north have contributed to the early end of the rainy season, which normally lasts through mid-July. (IANS)