Temperatures soared into the triple digits and tied a national record in Japan on Monday, part of a sweltering heat wave that has swallowed the archipelago. Hamamatsu, a coastal city in Shizuoka Prefecture on the island of Honshu, hit 106 degrees (41.1 Celsius) on Monday. It tied a national record set in 2018 and occurred within a day of Death Valley in California recording one of the hottest temperatures observed on Earth.

The brutal temperatures stem from a serious dome of heat stretching from the Korean Peninsula to southern Japan, a system that is likely to remain in place for much of the upcoming week. Temperatures about 10 to 15 degrees above normal are likely through the week across the entirety of the Japanese island chain, with only a brief return to more temperate conditions by the weekend. Anomalous heat is likely to return into next week.

In Tokyo, the high temperature Monday was 99 degrees, well above the average high of 88. Even more impressive than the heat was the sultry, oppressive moisture that accompanied it. Dew points climbed to 81 degrees. The dew point is a measure of how much moisture is in the air; 60s are humid, and 70s are tropical.

Factoring in the humidity, the heat index — a proxy for how much strain the human body faces because of the heat and humidity — soared to an astonishing 115 degrees. Osaka hit 100 degrees just a few minutes after noontime Monday. Their heat index was a degree higher, coming in at 116 degrees. Hiroshima saw temperatures climb well into the 90s.