New cold air headed into the eastern half of the nation yesterday, promising to bring weekend temperatures back below normal after two days of respite.

Weather forecasters said that temperatures would be below 10 degrees today in the Great Lakes region and the upper Mississippi Valley.

The Federal Energy Administration estimated that more than 1.5 million persons are out of work because of business closing for lack of natural gas. United Press International said its survey showed the total might be almost 3 million.

Although natural gas diverted from western states was en route to the East, there was little likelihood of businesses reopening soon. The gas is to be used first for homes and hospitals.

The Delmarva Power and Light Co. announced that it is halting natural gas deliveries to 104 Delaware industrial customers. The indefinite cutoff were necessitated by notification from Transcontinental Pipe Line Corp. of Houston that it would reduce Delmarva's supply by a further 10 per cent.

In addition to the 150 million cubic feet a day of natural gas that Federal Power Commission Chairman Richard L. Dunham ordered diverted to the East under the powers of the Natural Gas Emergency Act, supplies are arriving from Canada and Mexico.

Mexico began sending 40 million cubic feet a day and promised to continue for 60 days. Canada is selling 20 million cubic feet a day for 60 days. Twenty million cubic feet of natural gas would supply a town of 10,000 people for about five days.

The Federal Energy Administration announced that the extremely cold winter has caused record consumption of heating oil and other petroleum products, but that supplies appeared to be adequate.

An average of 5.2 million barrels of heating oil were burned daily during January, 21 per cent more than a year ago, the FEA said. Residual oil consumption was up 13.6 per cent over January, 1976.

Buffalo, N.Y., and Preston County, West Virginia, continued to be two of the most seriously affected areas.

A new blizzard was predicted for Buffalo where all but essential vehicles were barred from the streets to faciliate digging out operations by crews including soldiers and National Guardsmen.

Sen. Jacob K. Javits (R-N.Y.) toured western New York by helicopter and said he would continue to urge President Carter to declare the region a disaster area.

The New York Public Service Commission said about 400,000 workers were idled in the state.

Preston County, in the corner formed by Western Maryland and Southwestern Pennsylvania, has received more than 200 inches of snow this winter and more fell yesterday.

RIchard Wolfe, the county director of emergency services, told the Associated Press that, "It's been a losing battle."

"As soon as we get a road cleared, the wind shifts the snow and buries it again. We thought the weather was improving yesterday, but now we're starting the cycle over again - making deliveries of food and fuel to the same people a second time," Wolfe said.

West Virginia Gov. Jay Rockefeller canceled a $164,000 gold-leaf coating for the state Capitol dome and announced instead that a $95,000 snowblower would be bought for Preston County.

In Charleston, W.Va., the Columbia Gas Transmission Corp. announced that heavy demand had reduced its ability to deliver gas to the 80 retail utilities it serves in seven states and the District of Columbia.

"This action means that should extremely cold weather occur during the next two months, retail gas companies served by the transmission company will be forced to implement emergency curtailment activity at a higher temperature than in the past," a spokesman for the company told the Associated Press.

Weather experts had some good news yesterday, saying that when the snow covering the Northeast melts there is little danger of flooding.

Robert A. Clark, the National Weather Service's associated director for hydrology, said the flood threat is most serious along the Ohio RIver and the Kanawha River in West Virginia.

"The potential for flooding is not extremely serious," he told the AP. "We would need fairly rapid thawing combined with warm rain to really get into trouble."

Barges moved up the 981-mile long Ohio RIver for the first time in almost three weeks yesterday. The barges brought fuel oil, coal and rock salt.

In another development a spokesman for the fertilizer industry said the natural gas shortage is creating a shortage of nitrogen fertilzer which may reduce farmers' yields and drive up food prices. Ammonia, produced from natural gas, is the source of nitrogen for fertilizers.