Washington Gas Light Co. asked yesterday for a temporary 4.9 percent increase in natural gas rates in the District of Columbia.

If approved by the D.C. Public Service Commission, the average increase in monthly bills for consumers whose homes are heated by gas would be $2.

Monthly bills would go up an average of 45 cents for consumers who use gas for cooking or heating water, but not for home heating.

The increase asked by the gas company is only an interim measure. It would remain in effect while the Public Service Commission completes action on a permanent rate increase requested last summer by Washington Gas.

The permanent rate increase requested by the company would cost gas users $17.4 million a year. The temporary increase would total $4.8 million a year.

Washington Gas said the temporary raise is needed because the company is losing money in the District of Columbia. The loss on D.C. operations amounted to $2.6 million last year, the company said.

In requesting the interim increase, Washington Gas noted that "all groups involved in the permanent case have basically agreed that there is a need for some increase in the gas company's rates."

The gas company said the $4.8 million interim increase it requested represents the smallest permanent raise recommended by participants in the full rate case.

The gas company said it needs the full $17.4 million, but said it was asking this smaller temporary increase "to reduce controversy and enable the commission to act quickly."

Unless it gets an interim raise, it will have trouble obtaining long-term financing at a reasonable interest rate, Washington Gas said.

If the Public Service Commission grants the temporary $4.8 million increase, then later decides bills should not be raised that much, the gas company would have to refund the excess.

The temporary increase requested would boost the average monthly bill from $47.53 to $49.47 for homes that use gas for heating. The average monthly bill for nonheating gas customers would go from $10.61 to $11.03.