Temperatures hit 100 at the Custom House in Baltimore yesterday, marking the seventh day of a heat wave that has claimed the life of a city woman.
It was the state's first heat-related death since the summer of 1995.
More hot weather is expected today, though temperatures are not expected to rise beyond the low 90s. And the humidity should remain low, forecasters said yesterday.
A relative of Dorothy Mae Jefferson, 62, of the 800 block of N. Rose St. in East Baltimore found her body at 7: 20 a.m. Wednesday, a spokesman for the state Department of Health and Mental Hygiene said yesterday. She was lying in her bed.
Heat contributed to her death, though the primary cause was hardening of the arteries. Dr. John E. Smialek, Maryland's chief medical examiner, said Jefferson suffered from hyperthermia. In cases of hyperthermia, the body's core temperature exceeds 105 degrees.
There was no air conditioner or fan in her room, where the temperature was measured at 90 degrees.
A weak cold front from Canada was expected to move through the area last night, triggering thunderstorms and moderating temperatures.
That would break the three-day streak of 100-degree temperatures in Baltimore. At Baltimore-Washington International Airport, the high was 99 yesterday.
In Maryland, any stretch of three days or more when temperatures reach 90 degrees or higher is traditionally called a heat wave. But meteorologists say there is no official definition.
"A heat wave in Vermont might be totally different than a heat wave in Dallas, Texas, simply because 95 degrees in August might be typical, and 95 degrees in Vermont may not be typical," said Bill Sammler, a meteorologist with the National Weather Service in Wakefield, Va.
Despite the fatality, the recent stretch of hot weather is by no means the longest or most brutal that Maryland has endured.
Perhaps the worst heat waves of this century hit Maryland and the Baltimore area in 1901, 1918, 1934, 1936, 1988 and 1995. During each, temperatures either spiked repeatedly above 100 degrees or the hot weather hung around for weeks -- or both.
The summer of 1936 ushered in an eight-day heat wave that peaked July 10, when the mercury spurted to 107.4 degrees at 3 p.m. in downtown Baltimore. It remains the hottest day ever recorded in the city.
The longest heat wave came in the summer of 1995 -- the same season that more than 1,000 people died in the Midwest and Northeast in what was termed a "weather disaster."
Between July 12 and Aug. 5, Maryland sweated out a 25-day stretch of sizzling temperatures.
But the peak of the discomfort came between July 14 and July 16 of that year, when temperatures exceeded 100 degrees and the dew point reached levels typically seen at the equator.
People living in the urban areas of the Northeast and Midwest are more vulnerable to the heat. That's because they're not physically or psychologically adapted to live in sweltering conditions for long stretches. Big cities trap heat, and many poor and elderly people live in tenements or rowhouses without air conditioning.
Brick rowhouses with tar roofs are particularly hot. "They're literally like brick ovens," said Laurence S. Kalkstein, professor at the Center for Climatic Research at the University of Delaware.
About 175 heat-related deaths occur each summer in the United States, the National Weather Service reports. But in some years, the number of casualties to hot weather soars.
Heat waves "may be the most important weather-related cause of death in the United States, more than lightning, hurricanes and tornadoes," Kalkstein said.
Killer heat waves, he said, are typically marked by high overnight temperatures, not just elevated daytime peaks. That gives people less chance to recover from the stress.
In most of the fatalities, heat is a contributing cause of death. The primary cause, typically, is heart disease or respiratory failure. Occasionally people succumb directly to heat stroke, in which the body's ability to regulate its temperature fails catastrophically.
It's not the humidity
High humidity also marks deadly heat waves. Humidity curbs the body's ability to shed heat through sweating, because the air is too damp to absorb the sweat quickly.
Despite a string of high temperatures between 95 and about 100 over the past week, humidity remained relatively low.
"Humidities haven't been extreme, not like those two or three days in 1995," Sammler said. "Nothing close to them."
And while it's been hot, it hasn't been all that hot.
"Temperatures have not gotten over 100 degrees over a large area for any stretch of time," Sammler said. "I don't think anybody could classify that as severe."
With low humidity, this weekend should be nice.
"We're going to get a pretty good break," Sammler said. "It's the third weekend in a row where temperatures are supposed to turn pleasant."
B6 Here's a sampling of Baltimore's worst heat waves:
-- Temperatures are higher than 90 degrees for 15 straight days, from June 22 to July 6.
1918 -- An eight-day heat wave peaks on July 18, when Baltimore sets what is then a record of 105.
-- Hot weather lasts for 18 straight days, from June 21 to July 8. Temperatures go as high as 105 degrees. The Sun reports that "thousands" of people sleep on porches, front steps and in city parks.
1936 -- An eight-day heat wave peaks on July 10, when Baltimore sets a record of 107.4 degrees, which stands today. Twenty-nine people are hospitalized. Office and factory workers are sent home. State offices close.
1988 -- During the hottest overall summer in 116 years, the region swelters for 21 days -- from July 29 to Aug. 18. It is then the longest heat wave on record. One death by heat stroke is reported.
1995 -- A heat wave lasts from July 12 to Aug. 5 -- 25 days. It sets a record.
Pub Date: 7/19/97