The mercury reached a dangerous 40.2 degrees Celsius in Niigata Prefecture on Thursday -- the first time anywhere in Japan that temperatures have hit the 40- degree mark in the month of September.

The record temperature for September was observed in the city of Sanjo near the Sea of Japan coast shortly before 2:00 p.m.

Temperatures soared across much of Japan on Monday.

Some cities in southwestern Japan saw the mercury exceed 35 degrees Celsius. Weather officials say the heat will linger on Tuesday.