Last winter may have been mild, but now, temperatures are plunging in the Midwest – some 20 to 30 degrees below normal. The arctic blast, which is moving through the Ohio Valley into the Northeast, coincides with a historic increase in home heating costs this winter, particularly in New England.

The deep freeze is expected to last into the weekend.

“The cold air started moving into Minnesota, Wisconsin, and the Great Lakes area over the weekend and was firmly entrenched in those areas before moving into Ohio, Pennsylvania, and New York,” says Jim Keeney, a meteorologist with the National Weather Service.

The most frigid place is the upper Midwest, where the highest temperatures on Tuesday and Wednesday were forecast to be below zero. Temperatures toppled most dramatically in upper Minnesota and Michigan: For example, International Falls, Minn., which is located across from Fort Frances, Ontario, is expected to have a low overnight Tuesday nearing 30 degrees below zero. By Tuesday afternoon, temperatures in Duluth, Minn., had already fallen to 20 degrees below zero.

It is rare for temperatures to fall so precipitously without snow on the ground. Chicago, typically deluged by the white stuff at this point in the season, has gone 330 days without an inch of snow, breaking a record set in 1899. The low temperature Tuesday was 1 below. In Milwaukee, where snow is also absent, Tuesday’s low temperature was 5 below.

The cold front will generate lake-effect snow in the Great Lakes region through Wednesday. The lowest temperature recorded so far Tuesday in this region was at the Ann Arbor municipal airport in southeastern Michigan – 7 below.

So far, no overnight deaths have been reported related to the cold snap. Emergency shelters have been opened in most cities. In Milwaukee, the United Way donated $50,000 Monday to help open overflow centers for the homeless.

School closings and power outages were reported in some of the most frigid areas. More than 30 school districts in Michigan and dozens in Minnesota canceled classes or delayed start times Tuesday. Thousands of households lost power Sunday in Detroit, but they were switched back on Monday, DTE Energy reported.

Radiators and home heating systems are expected to be operating at full capacity this week. Overall this winter, homeowners will face unprecedented heating costs related to rising oil and natural gas prices.

Oil customers will pay a record-high average of $2,544 this winter, which is about $450 more than they paid last winter, according to a report released last month by the US Energy Information Administration (EIA).

Higher consumption this year, following last year’s record-breaking warmth, is one reason oil prices are going up, says Tancred Lidderdale, an energy analyst at EIA.

However, oil prices are projected to fall next winter because of increased US production and expected relative stability over the next 12 months in producing countries overseas. “We’re seeing record growth in crude-oil production in 2012, and we expect a new record to be set in 2013,” Mr. Lidderdale says.

Homeowners heating their homes with natural gas, particularly in the Northeast, will also see a surge in pricing this year. The average cost for homeowners will be $1,031, which is $200 more than last year, the agency reports. More than half (51 percent) of homeowners in the Northeast heat their homes using natural gas, while just a third (32 percent) use oil heat.

Natural gas cost increases are due to higher infrastructure costs and the difficulties of supplying gas to the Northeast. New England’s natural gas supply is easily disrupted, EIA announced last week, because its most densely populated areas, the Boston metropolitan area and New York City, do not yet have direct links to the natural gas pipeline network.

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In contrast, Pennsylvania, Ohio, and West Virginia are generally “more self-sufficient in terms of gas needs,” says Christopher Peterson, a lead economist with the EIA who specializes in natural gas.

“We’re adding a lot of pipeline capacity as a whole, but we haven’t quite yet solved adding capacity directly into [the New England market], where constraints can, at times, lead to elevated prices,” says Mr. Peterson.