US energy prices for home heating fuel surge as ‘polar vortex’ moves toward the country

US energy prices for home heating fuel surged as the “polar vortex” moved toward the country, rekindling volatility in markets that had been dormant after years of mild winters.

Natural gas prices jumped 4% over the past week and 14% over the past month, with benchmark Henry Hub trading at $3.66 per million British thermal units on Thursday. Contracts rose to $4.20 per million British thermal units on Monday.

Heating oil futures have gained 5% in the space of a week, with benchmark New York Harbor futures trading at about $2.35 a gallon on Thursday.

The northern United States could see its coldest January in more than a decade, after years of warmer winter temperatures, catching some market participants by surprise. Last year’s U.S. winter was the warmest on record, according to the National Centers for Environmental Information.

“The market has been fairly content with U.S. production and fuel inventories above normal,” said Phil Flynn, an analyst at Price. “But at the same time, the market may have to face a winter challenge it hasn’t seen in a long time.” About 47% of U.S. households use gas to heat their homes, while 40% use electricity, according to the U.S. Census. Heating oil is still used in some parts of the Northeast.

The jump in fuel prices comes as the eastern and central parts of the country brace for an arctic storm that is set to bring what the National Weather Service has warned could be the coldest air of the season so far and dangerous wind chills.

The agency warned that temperatures could drop below zero as far south as the Gulf Coast and Florida, potentially damaging citrus crops.

Flynn warned that the price impact could be significant if the forecasts are correct, noting that the arctic cold over Texas shale basins could disrupt supplies just as calm weather has reduced wind power production. That could push natural gas prices up by more than a dollar, he said.

The U.S. Energy Information Administration expects household winter heating spending to remain relatively unchanged from last year, with the exception of the Midwest, which is expected to see an 11 percent increase in gas prices this year and a 6 percent increase in electricity prices. Electricity prices in the Northeast are also expected to rise 5 percent.

A recent analysis of census data from Lodging Tree found that more than a third of U.S. households cut or skipped essential expenses like food and medicine last year to pay for utilities. Nearly a quarter of households were unable to pay part or all of their bills during that period.