The long weekend that traditionally marks the end of summer came to a close here yesterday by burning another firery page into the weather record book while thousands of vacationers made a relatively smooth return home.

The Labor Day weekend ended, and September began on a day on which the mercury ascended to 99 degrees, equalling a record for the date set in 1953.

While auto traffic returning from ocean and bay resorts was described as extremely heavy at times last night, no major tieups were reported on the Bay Bridge or its approaches.

At 1 p.m. the count of the number of westbound vehicles crossing in the previous hour was given as 2,012. It rose each hour to an 8 p.m. peak of 2,743.

The 9 p.m. count sagged to 2,613, and a police supervisor said "It seems like it's going to taper off." Indeed, the 10 p.m. count was 450 less, and that at 11 p.m. well below 2,000.

There was no immediate indication, however, that the torrid temperatures this weekend were keeping the number of homebound motorists below record levels.

National Airport operations officer Jim Kastner described the terminal there as "not that busy" last night, and speculated that the nation's economic recession might have curbed peoples' air travel plans.

An Amtrak spokesman said weekend traffic was heavy, particularly between Washington and New York, but appeared to be relatively free of snarls.

Yesterday, the 49th day this summer on which the temperature climbed to 90 or above, did nothing to diminish the possibility that this might be the hottest September here, just as July was the hottest July ever recorded and August was the hottest August.

Moreover, August, during which the average daily temperature was 82.8 degrees, was the hottest month ever endured here. The second hottest month was its predecessor, July, during which the average daily temperature was 82.3.