Arctic chill and heavy snowfall left tens of thousands of households in southeastern Europe without electricity and roiled the region’s power markets as rivers froze over, cables failed and generation plants reduced output or shut down.

Hydroelectric production plummeted in the Balkans as temperatures fell as low as minus 20 degrees Celsius (minus 4 Fahrenheit) and parts of the Danube river were almost entirely covered with ice. From Hungary to Bulgaria, day-ahead power prices jumped, in some cases to record levels.

“The market is really panicking because of the extreme weather,” said Tamas Migaly, a trader with energy broker 42 Financial Services AS in Prague. “With all these outages, people just don’t know what to expect.”

Power prices jumped to unprecedented levels in Hungary, with the spot price for round-the-clock delivery jumping to 200 euros ($210) a megawatt-hour on Tuesday and fluctuating, Migaly said. Serbian contracts shot to a record on Tuesday, reaching about 150 euros a megawatt-hour, according to Milos Mladenovic, managing director of the Seepex exchange in Belgrade. The price for same-day electricity on Bulgaria’s Ibex exchange peaked at about 122.81 euros a megawatt-hour, according to the exchange’s website.

Bulgaria, Romania and Serbia deployed emergency services to evacuate remote villages where people were stranded without electricity or heat. Around 23,000 Bulgarian households have been left without electricity and the country’s two main Black Sea ports were closed due to severe weather conditions. In Romania, about 14,000 households have been stranded.

From Croatia to Turkey, the unusually cold weather in the Balkans may persist throughout the week, according to MDA Weather Services. Temperatures in the region are forecast to average minus 6.4 degrees Celsius next week, 6.8 degrees below the 10-year average, according to The Weather Co. data.

Romanian electricity consumption rose to a 15-year high, Deputy Energy Minister Corina Popescu said. Daily power demand in Serbia was 18 percent above the average for this time of the year, according to state-owned power producer EPS.

“The whole region is relatively dependent on hydro plants, which now produce less than usual while consumption soars,” Mladenovic said.

The power shortage in the region is further exacerbated by nuclear outages. Romania had to disconnect its 700-megawatt Cernavoda-1 reactor twice in the past week after a blizzard damaged a high-voltage power line. Hungary, which already had outages at several thermal stations, plans to switch off its Paks-2 reactor for 3 days on Jan. 13.

Prices throughout Europe have risen amid the cold, with the French contract for next week jumping as much as 99 percent on Tuesday and 29 percent on Wednesday, while Hungarian day-ahead prices jumped 110 percent to a record yesterday, according to broker data compiled by Bloomberg.

Bulgaria declined emergency requests for power from Greece and Turkey amid heavy snowfall, Energy Minister Temenuzhka Petkova said Tuesday in the capital Sofia. The country was itself turned down by Romania two days ago and Greece said it would stop electricity exports to Bulgaria from noon Wednesday. Greek Energy Minister George Stathakis called an emergency meeting on Tuesday and urged consumers to avoid unnecessary consumption of power and gas during the peak hours from 6 p.m. to midnight.