Christmas week may be the most hazardous time of the year for street people in Washington and other cities, the U.S. Center for Disease Control reported yesterday.

Of 54 persons who died of exposure-related hypothermia in Washington over slightly more than 10 years, 11 died during Christmas week, according to a study by researcher Phil Nieberg, published in the center's Morbidity and Mortality Weekly Report.

Of the 54 cold-weather victims between October 1971 and January 1982 -- 42 of whom were black males -- 27 lacked adequate housing, 25 had no fixed addresses and 25 had blood alcohol levels above 0.15 percent of blood volume. (In most jurisdictions, a driver with a blood alcohol level above 0.10 is considered drunk.)

While the study covered only Washington, similar results probably would have been found in other big cities, the researcher said.

Christmas week, researcher Nieberg reported, is a particularly lonely time for the victims because most are poor and homeless and the holidays "are not a good time for them."

Alcohol poses a complication in hypothermia, he said, because drinking makes a person feel warmer than he really is and also impairs the ability of the skin to insulate the body from the cold.

Of the victims, Nieberg reported, 37 percent were found in various stages of undress, apparently the result of an "exaggerated sensation of heat" as body temperatures fall.

Since many victims are taken to detoxification centers rather than hospitals, the center urged that these detoxification centers take the temperatures of people admitted for treatment and act accordingly. It also called on hospitals to provide proper training and equipment for treating hypothermia.

Also, the center recommended, people released from jails and hospitals should be sent directly to shelters and not simply turned out onto the streets