The rising figures, and rising rate of positive tests, come as health officials in Philadelphia and Allegheny County, home to Pittsburgh, point to people socializing in bars and returning from beach vacations and travel to coronavirus hot spots in other parts of the U.S.
Officials said there were more than 830 people who tested positive for COVID-19 on Wednesday, bringing the statewide total to above 88,000. The state last recorded more than 800 new positive tests in May. It also reported another 25 coronavirus-related deaths for a statewide total of 6,712 since early March.
While the state's hospitalizations for the virus have continued to fall, officials said the percentage of people testing positive has been rising the last two weeks.
Gov. Tom Wolf's administration moved Wednesday to expand its indoor mask order to public places outdoors where social-distancing is impossible.
Under the new order, a mask or face covering must be worn whenever anyone leaves their home and where it is consistently impossible to remain six feet away from other people.
In Philadelphia, city officials on Tuesday halted plans to allow indoor dining, bars, gyms and fitness centers to reopen, with officials saying its new case increases of over 100 each day are too many.
Allegheny County reported more than 230 new coronavirus cases Wednesday, a day after it reported a single-day high of 110.
"While an increase in the number of cases was expected - this is larger than expected," county officials said in a statement. "The expectation is that the numbers will also significantly increase again tomorrow."
On Twitter, Lt. Gov. John Fetterman, who lives in Allegheny County, called Thursday's figure "truly alarming." The county's percentage of positive tests and hospitalizations are also on the rise.
County health authorities say the median age of the people testing positive is 29. They are asking residents to consider postponing plans to travel to a coronavirus hot spot, and to self-quarantine for 14 days and get tested when returning.
The county, Pennsylvania's second-most populous after Philadelphia, had avoided the higher case counts that hit Philadelphia and much of eastern Pennsylvania in the spring.
The Associated Press contributed to this report.