A study shows that heavy rainfall is becoming more common across Japan.

The Japan Meteorological Agency found that hourly rainfall records were broken in 2012 or later at 30 percent or so of all precipitation measurement stations across Japan.

Those sites include some in northern Japan, where heavy rainfall used to be relatively rare occurrences.

The JMA wanted to ascertain if hourly precipitation records had been broken at each of the 1,232 measurement stations where at least 10 years’ worth of statistical data is available.

It found that new records had been set during the period at 351 sites in 45 of the nation’s 47 prefectures, except Yamanashi and Saga prefectures.

The largest number, 83, were located in Hokkaido, followed by Iwate and Akita prefectures in northern Honshu, at 22 and 14, respectively. Kagoshima Prefecture in Kyushu also scored 14.

Hourly rainfall of 150.0 millimeters, which was observed in Kosa, Kumamoto Prefecture, in June 2016, is the most severe of all similar records taken in Japan during the period from 2012 through the end of July 2017. Hourly precipitation of 129.5 mm was measured during torrential downpours that lashed Asakura, Fukuoka Prefecture, this past July, leaving 41 people dead or missing in northern Kyushu.

The JMA website defines heavy rain as "like a waterfall" when hourly precipitation reaches 50 mm or higher. When it hits 80 mm or more, it is described as "people feel terror."

Such downpours can cause water levels to rise without warning in small and midsize rivers, submerge underpasses, of which it is estimated there are 3,500 or so across Japan.

Scientists studying global warming say heavy downpours are more frequent when the amount of water vapor in the atmosphere increases.

“The study shows that rainfall exceeding people's expectations can occur in any part of Japan,” said Kazuhisa Tsuboki, a professor of meteorology with Nagoya University.