Join the Crowds Avoiding the Crowds in Europe : Trends: Shoulder season is no longer a secret, as more Americans see the Continent in early spring and late into fall.

You could be a pessimist and think of this as the end of summer. Or you could see it as the beginning of shoulder season.

For many years, this was a sort of secret among seasoned travelers to Europe: You forgot about June, July and August because the whole world was on vacation then, especially the Europeans in August. And you forgot about December, January, February and March because too much of the world was frozen then. That left April, May, September, October and November as the “shoulder” between high and low seasons, and a prime time for travelers whose plans were not limited by school schedules. A shoulder-season traveler could (and can) see Europe when it was not as hot, not as expensive and not as crowded.

But the word has been spreading about shoulder season. Between 1993 and 1994, European Travel Commission figures show, American air arrivals (both leisure and business) to Europe rose 15.9% in May (to 825,843), 8.5% in September (to 852,181) and 8.7% in November (to 506,135), while overall arrivals for the year were rising 7.5%. (October rose 2.4%, to 618,465.)

Spring and autumn in Europe remain far more placid than summer, when nearly a million Americans per month are landing in Europe’s airports. But if your last autumn trip to London or Paris or Rome was five years ago, and you’re going again this fall, you may notice more tour buses and fewer vacant hotel rooms this time.

Cost is a key factor. Though specific dates vary by location, most major carriers set their U.S.-Europe fares highest June 1-Sept. 30 and Dec. 15-24; lower for April 6-May 31 and Oct. 1-Oct. 31, and lowest for Nov. 1- Dec. 14 and Dec. 25-April 5. For nonstop flights between LAX and London that translates this year into round-trip economy fares (for weekend flights) of about $940 for July departures, about $820 for October and about $720 for November. Fare wars, such as the round of discounts that broke out as September began, and other discounts often push those prices down even further. In addition, many hotel rates in non-business destinations fall at summer’s end, and many tour operators reduce their rates as well.

“There’s definitely a pattern of more Americans going to Britain in fall and winter,” says Robin Prestage, spokesman for the British Tourist Authority in New York.

“The American well-to-do traveler prefers the fall season. The heat is gone, and the cultural life is back in the cities,” says Helmut Helas, regional director of the German National Tourist Office in Los Angeles.

Tourism officials theorize that most of the non-summer visitors are returning travelers who were introduced to Europe on a summer trip, but first-timers are apparently playing a role in this trend as well. At Trafalgar Tours, a major U.S. operator of bus tours in Europe, vice president for sales and marketing Peter McCormack reports a 40% increase in September European tour bookings over the last three years, and a 15% increase in October tours. The company’s European winter tour schedule (Nov. 1-March 31) has grown from infancy three years ago to roughly 6,000 travelers last winter.

At Globus & Cosmos tours, another major U.S. operator in Europe, president John Martinen reports that the travel season has been extending gradually for about 15 years. Previously, before June and after Labor Day, Martinen says, the volume of tour travelers “dropped like a waterfall. The busiest weekend used to be the Fourth of July weekend. Do you know the busiest time of year we have now? The third week in September.”

At Collette Tours, general manager Tom Souza estimates that the company’s shoulder-season business is up 20% over the last three years.

If demand for spring and fall European travel continues to rise, travelers may begin to find they’re neither avoiding crowds nor saving as much money as in former years. And in fact, Souza says, “some hotels have started bumping up rates in the September period because it’s now a busy time for them.”

But right now, all indications are that off-season travel is a boomlet, not a boom. In 1990, European Travel Commission statistics show, 36.5% of Europe-bound Americans arrived in June, July and August. By last year, the figure had inched down to just under 34%.

In France, spring and fall have long been strong tourism seasons. But in the last few years, notes tourist office spokesman Christopher Thorpe, many seasonal lodgings in Brittany and Normandy and other rural regions have been extending their schedules, moving forward their opening dates to before Easter and pushing back their closings into November. In Italy, meanwhile, tourism officials say the last two years have brought a strong surge in spring and fall travelers from the U.S., with high occupancy rates stretching into early November.

Reynolds travels anonymously at the newspaper’s expense, accepting no special discounts or subsidized trips. To reach him, write Travel Insider, Los Angeles Times, Times Mirror Square, Los Angeles 90053.