Though East Coast residents are traveling in healthy numbers this winter, many spurred on by icy fingers up and down their spines, and the travel industry is predicting a good spring and early summer showing. some doubts remain about the summer European season.

The question mark is the decline of the U.S. dollar overseas.

Travel agents are quick to point out that, so far, they see no lessening of the American vacationer's interest in trips to Europe in the face of higher prices overseas due to unfavorable exchange rates. The proliferation of low-cost transatlantic air fares appears to guarantee a supply of willing passengers to fill the jets.

Now comes the latest news from the Civil Aeronautics Board, which has just proposed to abolish most of the current forms of charter travel so bargain-hungry U.S. tourists will be able - perhaps by midsummer - to sign up for a new kind of charter flight without having to pay in advance, stay a minimum length of time, or buy a land package (hotel, sightseeing, etc.) to meet eligibility requirements.

But the specter of the weakened dollar remains. Recently, John Bertram, chairman of the European Travel Commission, had some refreshingly frank comments about the dollar and European travel during a telephone interview:

"We're extremely aware of the situation, there's no denying it," said Bertrani, who also is director of the Netherlands National Tourist Office in New York. The value of the dollar is down about 50 percent in some countries compared to a few years ago, Bertram said. European travel officials hope new low-cost air fares "will somewhat offset higher land prices," he said.

Bertram also advised Americans to "eat out for breakfast. Let those Europeans who have a lot of money" patronize the hotel restaurants and pay $5 or $6 for a continental breakfast. But what worries him, he said, is that some of the low air fares " invite travelers to go overseas on speculation." When they arrive in Europe, after paying "next to nothing" for the air fare without any land arrangements, they will be "hit by the high prices" for accommodations and food.

Bertram's advice to budget travelers: Seek advise from a travel agent and figure out in advance where you're going to stay and what it's going to cost.