The mercury hit 35 degrees Celsius or higher in many places across the country, mainly in mid-June.
"We hadn't expected midsummer-like atmospheric conditions to appear so early and the difference from normal to be so big," said Yoshinori Oikawa, head of the agency's Centre for Information on Climate Extremes. "We can say that this is an abnormally high temperature."
Oikawa warned that the average temperature in June-August might be like that of the last two years, which marked the highest ever for summer. He called on people to take steps to prevent heatstroke.
[Copyright The Jiji Press, Ltd.]