This past September was the hottest in more than 110 years thanks to a powerful high pressure system over the Pacific, according to the Meteorological Agency.
The average September temperature at 17 observation points where urbanization has an effect was 1.92 degrees higher than usual, the biggest leap since 1898, the agency said Monday.
Record highs were logged at 51 of the 154 observation points across the country. The mercury shot up particularly in the north, where the westerlies carried the Pacific high, the agency said.
The average temperature was 3.8 degrees higher than usual in Hokkaido and 3.5 degrees higher in Tohoku.
By contrast, the average temperature was 0.6 degree lower in the southern part of Kyushu and 0.3 degree lower in Okinawa.