An Arctic front is forecast to descend into the central and eastern U.S. later this week. Above-average temperatures will give way to below-normal conditions across the Mid-Atlantic and Northeast, bringing colder weather back to major metro areas through the end of the month.

The setup closely mirrors the December weather pattern that locked much of the eastern US into a prolonged cold spell, sending natural gas prices higher amid increased heating demand.

Marc Chenard, a senior branch forecaster with the U.S. Weather Prediction Center, was quoted by Bloomberg as saying that the Arctic front will arrive in the eastern U.S. by Thursday or Friday this week. He said the pattern will remain in place for the next ten days.

The Arctic blast is expected to be severe. Bloomberg data indicate that average forecast temperatures for Washington, D.C., over the next two weeks will run well below 30-year norms, with end-of-month readings dipping into the high teens.

Washington, D.C. heating degree days over the next two weeks are expected to be among the highest of the winter season.

In energy markets, higher HDDs result in more furnaces running and higher demand for natural gas, heating oil, and electricity. Traders and utilities track them closely because even small changes in HDD forecasts can move energy prices.

NatGas Futs...

Cold returns.