Researchers in Japan have found coronavirus death rates among people aged 40 and older from the 7th wave of infections that hit the country this summer were less than half that when the 6th wave that had started early this year peaked.

The group at the Japanese Association of Public Health Center Directors compared death rates among the approximately 550,000 people aged 40 and older who contracted COVID between January and August in ten prefectures, including Osaka and Ibaraki.

The head of the Japan Medical Association has suggested the current nationwide surge in newly confirmed coronavirus cases could be a third wave of infections in the country.

Association President Nakagawa Toshio told reporters on Wednesday that there have been clear signs of a resurgence in infections since last month. He added that the situation in Hokkaido is particularly worrisome.

Weather officials in Japan are urging caution against heatstroke as intense heat continues to grip wide areas of the country on Monday.

The Meteorological Agency says a high pressure system is covering western and central Japan, causing the mercury to shoot up. In some areas, the temperatures rose above 35 degrees Celsius before noon.

A heat wave continues to grip western and eastern Japan, with the daytime temperature topping 39 degrees Celsius in Hyogo Prefecture in the west on Sunday.

Temperatures rose to 39.2 degrees in Hyogo's Nishiwaki City, and over 38 degrees in the town of Hatoyama in Saitama, as well as Takahashi City in Okayama, and Ogaki City in Gifu.

An iconic tomcat that serves as the "lord" of an ancient castle in Okayama Prefecture, western Japan, is trying to fulfill his duty of greeting tourists in the intense heat.

Bicchu Matsuyama Castle is located in the city of Takahashi, which had a daytime high of 37.1 degrees Celsius on Wednesday. Temperatures in the city topped 35 degrees for 18 days in a row.

A prominent infectious disease expert in Japan is warning that the country is in the midst of second wave of the coronavirus outbreak. The alarm comes as the number of seriously ill patients has been rising.

The western prefecture of Osaka reported 187 new cases on Wednesday ... the most among the country's 47 prefectures. There were 65 seriously ill patients as of Tuesday ... more than double the figure for Tokyo.

People in Japan are enduring a "hazardous" heat wave. The temperature is again likely to approach 40 degrees Celsius in some areas on Sunday.

On Saturday, temperatures of 35 degrees or higher were registered at 278 of the 921 observation points in the country. That's the largest number so far this summer.

Japan continued to experience a sweltering summer heat wave on Thursday with daytime highs of over 35 degrees Celsius recorded in many areas.

The Meteorological Agency says a high pressure system covering vast areas from western through northeastern Japan, combined with an influx of warm air, is bringing clear skies and high temperatures to the archipelago.

Prime Minister Abe Shinzo is warning against a second wave of the coronavirus outbreak in Japan. He urged people not to expect the virus to weaken in the coming hot summer months.

Abe spoke during a program streamed live on Sunday night. He said people should not be complacent this summer because the virus is spreading even in extremely hot countries in the Middle East.