The massive deluge of rain knocked out a substation supplying power to Terminal A East around 5:30 p.m. Sunday.
35 arrivals and departures were cancelled this morning due to the outage - around a dozen of which were American Airlines flights.
Power is now back on over at ticketing, but remains out over at baggage claim. Travelers can collect their bags at other terminals until while crews work to repair the outage.
And since power came back on sooner than expected, airlines are now trying to reinstate some flights.
Sunday's strong storms set a record for one-day rainfall in Philadelphia.
The National Weather Service says 8.02 inches of rain fell in the city Sunday, shattering the previous record of 6.63 inches set during Tropical Storm Floyd on Sept. 16, 1999.
Heavy rains caused flash flooding, power outages and airport delays.
The soaking rains also flooded roads and caused traffic headaches.
Drier weather is on the way just in time for the start of the workweek.
Information from The Associated Press was used in this article.