Russians call September the "Barknatny Sizon" - the velvety season - here on the shore of the Black Sea. Ever since Czar Alexander III began coming here a century ago, that month has been considered the ideal time for a Crimean vacation.

The weather characteristically is dry and warm, but no uncomfortably hot. The water temperature of the Black Sea is still in the upper 60s. Best of all, the crowds are smaller than at the height of the vacation season in July and August. But even while smaller, the crowds are still too big for Yalta to feed adequately, house and entertain.

"People save up all year to come here," said a Yalta man, "but two-thirds of those who come can't be accommodated in established vacation facilities."

Local restaurants, bars, cafes and cafeterias can serve about 55,000 people at a sitting, according to Dmitry D. Vershkov, Yalta's mayor. But he said that on a given day there may be as many as 300,000 tourists here.

The city is even considering limiting the number of vacationers allowed to travel here by car, Vershkov added. There is no airport or trains station. The only other access is by sea or by bus from Simferople, about 60 miles over the mountains to the west. A limit on access by private car hopefully would clamp a lid on tourism.

What's happening in Yalta reflects a nationwide problem. A Soviet population increasingly anxious for "the good life" - and better able to afford it - wants improved vacation facilities. But the centrally planned Soviet economy seems unable to build them fast enough. The current five-year plan calls for a 12 per cent increase in holiday accomodations, but that would be a small step forward accommodating the fourfold increase projected for the year 2000.

The shortage of adequate vacation facilities is particularly perplexing to the Soviet leadership, since one of its favorite propaganda themes is the Soviet "right to rest." For millions, in fact, vacations are incredibly inexpensive thanks to huge government subsidies.

Warnings in the press attest to the size of the problem. "We stand at the very beginning of a recreation explosion," wrote demographer V. Perevedentsev in a recent issue of Literaturnaya Gazeta.

The term "vacation facilities" means something quite different here than it does in the West. Such phenomena as motels, fast-food outlets and recreational vehicles allow the Western vacationer to tailor his holiday to his own tastes. But such facilities are practically unheard of here, where the emphasis is on "organized vacations" in sanatoriums, rest homes and "pansionats" (holiday centers). All provide room and board, and admission is by "putyovka" - a pass distributed through trade unions, government ministries and individual factories.

Sanatoriums cater to vacationers with health problems - lung disorders, cardiovascular disease, nervous conditions - and are staffed by medical personnel. Rest homes are less regimented, but visitors are still expected to participate in group exercises and organized recreation. The holiday centers are like large boarding houses.

Lenin himself deemed the Crimea a health resort center. "All the splendid summer homes and mansions previously used by big landowners and capitalists, the palaces of former czars and grand dukes, shall be turned into sanatoriums and holiday homes for the workers and peasants," he directed in 1920.