Sun-baked and heat-weary, Washington underwent its 15th consecutive day of temperatures of 90 degrees or above yesterday, an experience in continuous sweltering unmatched in 107 years.

At the same time, the high temperature here boiled up out of the 90s yesterday to reach 100 degrees at National Airport at 5 p.m.

Neither the 15-day mark, nor the 100-degree reading set a record, but both came close.

When the mercury reached 100 for the first time this month and the fourth time this searing summer, it failed by only a single degree to match the all-time record for the date of 101 degrees set 50 years ago, in 1930.

And although Washington had gone 107 years without the torment of 15 successive days in a 90-degree oven, the city endured a longer period of similar temperatures once before -- 108 years ago.

In 1872, the year the National Weather Service began keeping its records, the mercury reached 90 or above on 18 straight days, between June 27 and July 14.

While it may be of small consolation to suffering area residents, forecasters say that record could be equalled or surpassed in the next few days.

"If we make it through Monday (in the 90s), we'll tie that," said forecaster Charlie Chilton. "It's not something to look forward to."

But it cannot be easily ruled out. The official forecast calls for a high today from 95 to 99. The high Sunday is expected to be from 90 to 95.

However, some hope exists. A weak cold front is spreading over the northern Great Lakes. Many of its predecessors have stalled north of Washington this summer and thus have furnished little relief. Although this one also is expected to stall, Chilton said, clouds associated with it might nevertheless drift into the area.

They might provide enough cover from the relentless summer sun to hold the temperature on Sunday and Monday below 90 and thus keep the consecutive day record intact, he said.

But Chilton said, no indication can now be seen of any true break in the choking grip of the record-setting summer's fiery heat and suffocating humidity.

"Heat waves tend to be sort of self-perpetuating," he said, "especially when they start early in the summer."

This month follows one that was the hottest in Washington weather history, with temperatures of 90 or above on 21 days, with temperatures of 100 or above on three days, and with the highest average temperature ever recorded here.