Yes

Based on the weather in Philadelphia International Airport (PHL), 8000 Essington Ave, Philadelphia, PA 19153, USA as of October 17, 2017 5:37am local time

Why? Because it's cold. simple as that.
Current Conditions
Clear
Temp: 40.1°F4.5°C
Wind: 2 MPH3.2 KPH
Precipitation: None