Despite it still officially being the rainy season, Japan continued to see temperatures above 37 degrees Celsius in numerous places Monday, raising the prospect that the government could issue a newly created top-level special heatstroke alert any day.
On Monday at 2 p.m., an observation point in the city of Shingu, Wakayama Prefecture, logged 39.6 C, the highest-ever temperature recorded in the city, while a spot in Fuchu, western Tokyo, saw the mercury rise to 39.2 C, also an all-time record high. Several other places, from Mie to Chiba to Ibaraki to Saitama, recorded temperatures topping 37.5 C.
The Meteorological Agency classifies days topping 35 C as ※extremely hot days.§
On Monday, a heatstroke alert was issued in 27 of the nation＊s 47 prefectures, including seven prefectures in the Kanto region that includes Tokyo, three prefectures in the Tokai region and another three prefectures in the Kinki region.
A special warning alert is one level above the regular heatstroke alert and has never been issued since its establishment in April this year. The top-level alert is issued when the wet-bulb globe temperature (WBGT), a heat index based on factors such as air temperature, radiant heat and humidity, is expected to hit at least 35 C at all monitoring points in a prefecture the following day. As of 2 p.m. on Monday, Tokyo＊s heat index was at 33.3 C.
WBGT temperatures that would prompt a top-level warning present a serious threat to human health. People are asked to stay indoors, turn on air conditioning and stay hydrated, and municipalities are urged to open designated cooling shelters to the public.
A regular heatstroke alert is issued when the WBGT index reaches 33 C at a monitoring post in a prefecture.
Katsumasa Yagi, an official at the weather consultation bureau of the Meteorological Agency, attributed the dangerously high temperatures during the rainy season to a ※strong extension of the high-pressure system in the Pacific Ocean.§
In Kanto, however, the extension of the high-pressure system will weaken and cloudy and rainy weather is expected from Wednesday, he said.
※From the day after tomorrow, cloudy weather is forecast because the rainy season front will move southward, resulting in a continuation of cloudy and rainy days,§ he added.
Climate change, which is primarily caused by the burning of fossil fuels, also contributes to the strength of heat waves.
The end of the rainy season has yet to be announced by the agency. Apart from Okinawa and Amami Islands in Kagoshima Prefecture, for which the season was declared over in late June, Japan normally expects the season to end around mid-July and late July.
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