A cold blast across China that’s brought temperatures in Beijing to the lowest since 1966 is wreaking havoc on energy markets, creating record power demand and sending coal and gas prices soaring. Nine northern provincial power grids, including in Beijing, reached record-high loads this week as heating demand surges, according to state-owned CCTV News. Coal prices have risen more than 4% this week, while wholesale gas prices jumped to the highest in three years as import terminals are being hamstrung by strong winds and icy conditions.

Chinese thermal coal for May pared weekly gains on Friday, slipping 0.4% to 704.4 yuan ($109) a ton on the Zhengzhou Commodity Exchange. The contract gained 4.5% over the week.

Domestic LNG prices in Tangshan, east of Beijing, have more than doubled since late November to 8,600 yuan per ton, according to consultancy JLC. It’s the highest level since Feb. 2018, when a government push to reduce coal use caused widespread gas shortages.

Frigid weather has caused transportation disruptions, with LNG tankers being delayed in Qingdao because of high winds, according to a report from a government-run news portal.

South Korea’s electricity demand reached a record 90 gigawatts because of the chill, the Ministry of Trade, Industry and Energy said in a Jan. 7 report on its website. Most of the western part of the country was under a cold wave warning as of Friday afternoon.