SINGAPORE, Oct. 2— There is no real winter in tropical Southeast Asia. This year, though, the region may feel an unmistakable chill.

High oil prices deal a double-whammy to Southeast Asia's developing economies, raising the cost of energy while curbing demand for the exports the region depends on for growth. The prospect of fuel shortages and soaring prices in the industrialized West means possible trouble for Southeast Asian countries still struggling to put the financial crises of 1997 and 1998 behind them.

''If there's a bad winter, the chances for an oil shock are high,'' said William C. Belchere, the head of fixed-income research at Merrill Lynch in Singapore. ''That would hamper recovery in Asia.''

A taste of what could come is already rocking Indonesia, Southeast Asia's largest oil producer, where thousands protested today, demanding that the government scrap a day-old increase in fuel prices. There is widespread concern that further price increases could inflame social unrest in Indonesia -- even as the country earns more money from its oil exports.

The impact of higher energy prices also has hurt Southeast Asia's financial markets, where deepening political instability, persistent corruption scandals and sluggish efforts to invigorate industry and capital markets have sparked an exodus by foreign investors. For them, the uncertainty over oil is only the latest reason to reassess whether Southeast Asia is revamping its economies fast enough to remain competitive in the global economy.

Many economists say investors are overreacting. While oil's upsurge is likely to shave points off the region's economic growth rates, they say, it represents no singular economic catastrophe to Southeast Asia. Indeed, economists are divided over just how much direct impact rising oil prices might have on Asia's developing economies.

Southeast Asia is sitting on large pockets of natural gas and oil. Brunei, Vietnam and Malaysia, in addition to Indonesia, benefit from the latest trend. Some economists say they believe Southeast Asia is no more vulnerable to oil shocks than the rest of the world. Asia is one of the fastest-growing consumers of oil, but oil is responsible for less of its annual economic growth than it is in in the United States, according to David G. Fernandez, an economist at J. P. Morgan. Southeast Asia is, after all, less industrialized than the gas-guzzling economies of the West. Other economists say that developing economies are hit hardest by rising oil prices.

Some economists warn that by cutting into trade surpluses and fueling inflation, higher oil prices could accelerate this year's slide by regional currencies. That could prompt authorities to raise interest rates, thereby muting economic growth. There is agreement among economists on one thing: oil prices threaten demand for the exports Southeast Asia depends on for growth.

Photo: Indonesians line up for inexpensive kerosene in Jakarta yesterday. Recent increases in oil prices have caused protests. (Reuters)