Japanese authorities expect Friday to be another dangerously hot day and urge people across the country to continue taking precautions against heat stroke.

The Meteorological Agency expects daytime highs to surge across central and western regions. It says temperatures will reach 39 degrees Celsius in Nagoya City, 38 in Kyoto City, 37 in Osaka City, 36 in the cities of Kobe and Yokohama and 35 in Fukuoka City and central Tokyo.

The agency and the Environment Ministry have issued a heat stroke alert for 30 prefectures. Many people have been hospitalized with suspected symptoms this summer, with some cases leading to fatalities.

The authorities are advising people to stay indoors, refrain from exercise, use air conditioners and consume water and salt. They also say people should pay close attention to senior citizens, babies and younger children, as they are especially vulnerable.

Weather officials say the soaring temperatures and warm damp air will also cause localized thunderstorms. They are calling on people to stay vigilant against lightning, gusty winds and hail.

People should shelter in sturdy buildings and take other safety measures if they notice signs of developed rainclouds in their areas, such as sudden chilly winds.

Meanwhile, Severe Tropical Storm Maria is currently moving north over waters off the eastern coast of Japan. Weather officials say it will maintain this course through Monday. It will then approach northern Japan, bringing very stormy weather.

The sea off the Kanto and Tohoku regions is expected to start turning rough as early as Saturday, with winds also predicted to gather pace. Similar conditions may also be observed in waters off Hokkaido.