USAir Group Inc. said yesterday that it may lose $147 million to $179 million in the final quarter of the year as a result of the continuing high cost of jet fuel and a weak market for air travel.

The Arlington-based airline holding company said it was issuing the estimates of a loss of $3.50 to $4 per share because of a story in the Charlotte Observer in North Carolina that quoted an airline officer saying that USAir lost $100 million in September -- or $3 million a day. "While these numbers are approximately correct for the month of September, they do not represent earnings for either the fourth quarter or for 1990 as a whole," according to the airline's statement. Airline spokesman David Shipley declined to elaborate, saying, "We don't normally project earnings."

Buffeted by a weak economy and jet fuel costs that more than doubled after Iraq invaded Kuwait in August, USAir and most other airlines are expecting a dismal fourth quarter. For the year, USAir estimated that its losses will be approximately $441 million, or $10 a share. The carrier reported a net loss of $120 million in the third quarter of 1990. In the first nine months of the year, it lost $233 million on revenue of $4.9 billion. Last fall, it laid off some 3,600 workers as part of a cost-cutting effort.

The estimated earnings "are not surprising," said Edward Starkman, an analyst with Paine Webber Inc. in New York. Starkman noted that fuel prices have moderated since September, and said that other airlines might have lost similar amounts per day in September.

USAir's stock closed unchanged in trading on the New York Stock Exchange yesterday at $15.25.