China’s massive fleet of coal and gas power plants logged the first year-on-year gain in electricity generation for 2025 following blistering heat that baked parts of the country.

Thermal power output in May rose 1.2% from a year earlier, the first gain since November, according to data from the National Bureau of Statistics released on Monday. Temperatures climbed across northern China ahead of the start of the meteorological summer in June, boosting the use of air conditioners.

While northern China was hot, some parts of the south were drenched by heavy rainfall, although that didn’t translate into higher hydropower output during the month. Generation fell 14%. Nuclear, wind and solar power all increased, but not enough to blunt the increase from thermal sources.

Still, output from fossil fuel plants for the year are so far down 3.1% from 2024 levels due to strong generation from wind and solar farms, and more tepid growth. China is the world’s largest importer of coal and gas, and purchases of both fuels have fallen so far in 2025.

China’s spot coal prices have dropped to the lowest level since 2021, and are down 30% over the past year.