Record Heat, Drought Threaten Japan’s Rice Harvest; Dams in Tohoku, Hokuriku at Critically Low Levels

The Yomiuri Shimbun

16:04 JST, August 2, 2025

The record-breaking heat and droughts this summer have raised concerns about the impact on crops, and high temperatures and low rainfall are expected to persist in August.

New average temperature records for June and July were set this year, according to the Japan Meteorological Agency, and there has been a surge in heatstroke patients in hospitals. Exacerbated by a lack of rain, crop growth is now being affected in key rice-producing areas such as the Tohoku and Hokuriku regions.

The data for the average monthly temperatures goes back over three decades.

The water level in some dams has fallen dramatically, and central and local governments are issuing urgent calls for water conservation.

In July, the number of locations which recorded a maximum temperature of 35 C or higher totaled 4,565, the most since comparable data became available in 2010.

Cases of heatstroke have also soared, with the Fire and Disaster Management Agency reporting a record 17,229 were transported by ambulance in June — the most in a month since it started collecting the data in 2010.

While the heat has been relentless, rainfall has been at record lows. The agency attributes this to a strong high-pressure system that has prevented rain clouds from developing.

As a result, many regions received less than half of their average rainfall in July, with the Sea of Japan side of the Tohoku and Hokuriku regions receiving only 13% and 8%, respectively.

Drought-stricken dams

“This year’s harvest will probably be smaller,” said a rice farmer from Asahi, Yamagata Prefecture, as he looked at his cracked paddy field.

He cultivates a local variety of rice on about seven hectares of land. However, there has been almost no rain since mid-July, causing a water shortage and prompting the tips of some of his rice plants to turn brown and wither.

The farmer move water in plastic tanks from a waterway located about 1.5 kilometers away. “How much longer can I hold out?” he wonders.

In response to concerns about the impact on rice plant growth, the Agriculture, Forestry and Fisheries Ministry plans to begin subsidizing the cost of installing pumps and other necessary equipment.

The drought is creating a critical situation in dams in the Tohoku and Hokuriku regions. According to the Land, Infrastructure, Transport and Tourism Ministry, as of Thursday, Gosho Dam in Morioka and Naruko Dam in Osaki, Miyagi Prefecture, were at 0% storage capacity, indicating that they were below their minimum water levels. Shozenji Dam in Joetsu, Niigata Prefecture, was down at just 12%.

Naruko Dam supplies water for agricultural purposes. Its remaining water is being released as an emergency measure during the crucial rice heading season.

“If it doesn’t rain, the water in this dam will be completely depleted in about two weeks,” an official at the dam’s management office said.

In response to the water shortage, the ministry has imposed restrictions on water intake from 19 rivers across the Tohoku and other regions. The ministry is urging residents in affected areas to conserve water.

“[This summer’s heat] is the result of a combination of factors, including the effects of global warming,” said Hisashi Nakamura, a professor emeritus at the University of Tokyo and an expert on global climate dynamics.

He explained that a strengthened Pacific high-pressure system is pushing the prevailing westerlies northward, resulting in notably high temperatures in northern Japan. Based on this, he stated that “the situation is unlikely to change significantly throughout the summer.” The agency’s forecast concurs, predicting further severe heat in August.

The agency anticipates that rainfall in some of the drier regions may return to average or above-average levels in August. However, it cautions that “it may not be enough to fully resolve the ongoing water shortage.”