TOKYO — Japan is sweltering through its hottest summer on record, weather officials said today.

Japan joined many parts of the Northern Hemisphere in seeing an unusually hot summer. Meteorologists say 17 nations have recorded all-time-high temperatures this year, more than in any other year, and scientists said July was the hottest month on record for the world's oceans.

Across Japan, temperatures soared higher than historical averages by 2.96 degrees from June through August, the highest since 1898 when records began, according to the Japan Meteorological Agency.

That's higher than the previous record set in summer 1994. In Tokyo, temperatures have climbed as high as 99 degrees, and more than 46,000 people have gone to the hospital this summer, the Fire and Disaster Management Agency said. Some 150 people died from heat stroke.

The heat, however, has been good for the economy. A government report this week showed retail sales rose 3.9 percent from a year earlier.