February's freezing temperatures could heat up earnings for Questar Corp., as the energy company's natural gas subsidiary has distributed record volumes of gas to customers in Utah and Wyoming.

Preliminary figures show Questar's Mountain Fuel Supply Co. set back-to-back records for supplying natural gas to its Utah and Wyoming customers during this past week. Onc Feb. 7, a five-year record of 707 million cubic feet of gas delivered in one-day was shattered when 719 million cubic feet of gas were delivered in a 24-hour period. The record fell the following day, when Mountain Fuel distributed 726.5 million cubic feet of gas.The company said its 476,500 customers should anticipate higher gas bills this month because of the cold weather. Those having problems with their bills should contact Mountain Fuel.

Also contributing to record deliveries are 10,500 new customers, and a 23 percent increase in industrial sales and interstate transportation volumes.

But Questar isn't about to declare 1989 a record year based on the increased business.

"This is an encouraging beginning to a new earnings year, although weather in our area is notoriously variable," Questar Chairman and President R.D. Cash said.

How much impact this winter will have on the entire fiscal year depends on the "swing months" of March and April.

"During the first part of last year temperatures were below normal, but then in March summer practically began," said spokesman Curt Burnett, noting this year's first quarter ending March 31 will probably be an improvement over the same period last year.

He explained that cold temperatures are the single most important factor on earnings because of how it affects every facet of Questar's integrated operations, from drilling to delivery.

But the retail gas distributor's improved earnings in 1988 couldn't overcome other factors that resulted in Questar's decreased profits.

The company had 1988 net income of $25.85 million, or $1.28 per share, compared with $25.93 million, or $1.33 per share, for the prior year. Results included a $19.9 million, or $1.03 per share, after-tax write-down of oil and gas properties due to a severe drop in oil prices in the third quarter.

Excluding the write-downs and charges, Questar in 1988 earned $45.78 million, or $2.31 per share, compared with $45.85 million, or $2.40 per share, for the prior-year period. The lower per-share earnings reflected a 4 percent increase in average common stock shares outstanding in 1988.

For the fourth quarter of 1988, however, Questar's net income was $14.16 million, or 72 cents per share.