For the first time in nearly two years, the mercury in Hagerstown weather observer Greg Keefer's thermometer rose to 100 degrees at 4:09 p.m. National Weather Service data indicated a Tuesday high in Hagerstown of 98 degrees, Zubrick said.
Washington County has seen only nine 100-degree days in this decade, and temperatures last reached the 100-degree mark on Aug. 16, 1997, according to Keefer's Web site.
Martinsburg, W.Va., logged a late Tuesday afternoon high of 104 degrees, making it the area's hot spot.
The high temperature in Williamsport was 101, while the mercury climbed to 100 in Boonsboro in Clear Spring. In Waynesboro, Pa., the high was 98 degrees, and the temperature reached 99 degrees in Chambersburg, Pa.
The steamy weather prompted the Maryland Department of Health and Mental Hygiene to issue a hot weather advisory on Tuesday, and the heat advisory issued by the National Weather Service remained in effect through Tuesday night, Zubrick said.
The heat wave took its toll on Tuesday.
Interstate 70 was littered with tractor-trailer tire recaps, as the searing heat on roadways caused the rubber to fly off the tire casings, said Gary Shank, assistant resident maintenance engineer for the State Highway Administration.
After several children suffered heat-related illnesses, the Washington County Parks and Recreation Department sent unhappy day campers home from Martin L. "Marty" Snook Memorial Park in Halfway at noon, Camp Supervisor Stacey McLeran said.
"It was just too darn hot outside today, and the kids have no way to get out of it," she said.
"To some extent we are getting more people in to get out of the heat," said Margaret Bream, the director of Franklin County, Pa., senior centers. She said the county's seven centers, which serve about 280 seniors daily, are air conditioned.
At the same time, some people who had made reservations to eat at the senior centers canceled because they didn't want to leave their air-conditioned homes, Bream said.
Midge Tehan, general manager of corporate communications at Allegheny Power, said the utility that serves Washington County had suffered no power outages during this time of high energy use.
The Pennsylvania Public Utility Commission on Tuesday afternoon issued a power usage reduction request to county governments, according to a PEMA notice.
"Obviously it's hot outside and people are using a lot of electricity," said Eric Levis, press secretary for the PUC.
He didn't know who sent the power reduction request the PUC received, but said some power companies were asking customers to reduce consumption by delaying chores such as laundry until the evening when demand would drop.
"They're not asking people to turn off the air conditioning because, obviously, safety comes first," Levis said.
In the midst of the fourth consecutive day of blistering temperatures, health care providers throughout the Tri-State area remained alert to the threat of heat-related illnesses.
"People are coping better than I expected," said Dr. Lawrence Boyler, an emergency room physician at Chambersburg Hospital in Chambersburg, Pa.
Boyler said he hasn't seen any classic heat stroke or heat exhaustion cases during the current heat wave, but he said the heat appeared to be exacerbating existing medical conditions, such as lung diseases or congestive heart failure.
Heat-related 911 calls in Berkeley County, W.Va., had averaged about one an hour since midnight Sunday with people complaining of chest pains and breathing problems, Berkeley County Emergency Services 911 dispatcher Sheila Hollis said.
Martinsburg City Hospital treated three people for heat exhaustion Monday, but a hospital spokeswoman said emergency room attendants were surprised they didn't see more.
"We had a couple people who were out in the sun a little too long and felt faint. We gave them fluids and some rest and they were ready to go after a couple hours," Laura Riggs said.
Jefferson Memorial Hospital in Ranson, W.Va., and War Memorial Hospital in Berkeley Springs, W.Va., also reported few problems from the heat.
"We've been very busy but we haven't seen much caused by the heat. We've had a lot of sunburns, poison ivy and bee stings," War Memorial spokeswoman Lyn Goodwin said.