With temperatures expected to climb this weekend, Aoyagi urged residents to drink plenty of water, visit air-conditioned buildings and avoid strenuous activities.
Fans are available for elderly residents and adults with disabilities through the county Department of Health and Human Services' Aging and Disability Services Information and Assistance Unit. Call 240-777-3000.
Of the county's 32 nursing homes, three remained without any power and nine others were using backup generators, but were not running air conditioners. The affected nursing homes account for more than 1,400 residents. County officials were still working to assess the status at the 50 small group homes in the area.
Pepco reported 22,887 customers still without power. The utility company expects to restore power to all customers some time over the weekend, said spokesman Clay Anderson.
"Considering the 160,000 we had last evening, most people will be back late tomorrow," he said.
More than 100 crews, some from Delmarva Power and Atlantic City Electric, were expected to work through the night, Anderson said.
During a press conference Thursday in the Long Branch neighborhood of Silver Spring, County Executive Isiah Leggett said the county is working with Pepco to restore power to homes and businesses as county employees work to reopen roads closed by downed trees and high waters, and provide power to traffic signals that were knocked out by the storm.
"We continue to work in the most aggressive manner to ensure that the most vulnerable in the community are protected," Leggett said, urging patience.
Leggett said the Gaithersburg and Laytonsville areas were hit hardest by three storm cells that swept through the area Wednesday.
Nineteen schools remained without power, down from 100 when the storm hit on Wednesday afternoon. School was canceled Thursday, disrupting final exam schedules for some. By 5 p.m., the school system had decided to open on time Friday, but officials said that some schools could remain closed.
Suburban, Adventist, Montgomery General and Holy Cross hospitals were operating on generator power, representatives said.
Lacefield reported 29 county roads were closed, all due to downed power lines. As of 4 p.m. about 60 traffic lights throughout the county were still without power. Three of the busiest intersections - Connecticut Avenue and East-West Highway, Norbeck Road and Georgia Avenue, Interstate 270 and Falls Road - were being run off generator power.
With all the downed trees and storm damage, no injuries had been reported, Lacefield said, although about 30 houses were damaged. Calls into the county's 9-1-1 center were up significantly from about 1,500 on a normal day, to 2,800 on Wednesday. Between 3 p.m. and 6 p.m. Wednesday, the 9-1-1 center received 1,200 calls, he said.
Montgomery County Fire and Rescue Service spokesman Pete Piringer, said there were 650 calls for emergency service from 3 p.m., Wednesday to 3 a.m., Thursday. Normally the county handles 375 calls in a 24-hour period.
"Most of them were wires, transformers, trees on houses and things of that nature," he said. "As you can tell we were extremely busy," he said.
In Poolesville, the town's Wastewater Treatment Plant took a beating but ultimately weathered the storm. A bolt of lightning hit the plant and damaged some of its monitoring equipment, according to an e-mail from Town Manager Wade Yost, but generators and a back-up system kicked in, and staff are operating the facility manually until replacement parts arrive.
Transmitting equipment and the fencing around Well No. 5 were also damaged by a falling pear tree, though the well itself was unharmed.
An estimated 160,000 gallons of raw sewage overflowed into Seneca Creek in the Germantown area as a result of Wednesday afternoon's thunderstorms, according to the Washington Suburban Sanitary Commission.
Kira Calm Lewis, a spokeswoman for the commission, said a loss of power from electrical lines serving the Seneca wastewater treatment plant in Germantown caused the overflow. Work crews have posted signs warning people to stay out of Seneca Creek for 30 days, Lewis said.
