The outage, PECO's second biggest on record, affected a total of 715,000 customers at its peak. The most widespread outage hit 850,000 during Superstorm Sandy.
Since the winter storm, 65 percent of power has been restored, according to PECO, but as temperatures plunged into the teens overnight, some areas were still in the dark.
"There are still 250,000 PECO customers without power, but we hope to restore full service by Friday evening," Cathy Engle Menendez, a PECO spokeswoman, said last night.
Menendez said Philadelphia experienced fewer outages than Bucks, Chester, Montgomery and Delaware counties.
PECO's website, PECO.com, offers an outage map that is updated every 15 minutes, officials said. Crews are on 16-hour shifts around the clock to restore power.
Area politicians reached out to constituents in some of the hardest hit areas via social media.
"I continue to be amazed by the resilience of the people in this community. I know this has been an awful experience made worse by the freezing temperatures," Bucks County state Rep. Steve Santarsiero wrote on his Facebook page. "Hopefully we are getting close to a resolution of all remaining problems."
There were 42 schools in the region without power as of yesterday, but with PECO crews working over the weekend, the schools were expected to open Monday.
Two Red Cross shelters - one at Hatboro-Horsham High and another at West Chester University - remained open last night, officials said.
Other residents waited out the outage in hotels - although with everyone clamoring for a room with power, finding one amid the blackout became a challenge.
In Malvern, the Desmond Hotel offered $20 off to those in need. Since Monday, their 194 suites have been solidly booked.
"We are happy to be able to help people in the community," general manager Michael Chain said. "Our staff has been working round-the-clock, crazy hours and are tired but energized."
The same goes for DoubleTree Suites in Plymouth Meeting, where the 253 suites have been booked solid since the start of the ice storm Wednesday.
"The phone won't stop ringing," said John Lowe, the DoubleTree's general manager. "We are keeping a waiting list, and as residents' power is restored, we refill the room as soon as possible."