Pack or skip
Thermal underwear for Philadelphia in December
Verdict
Pack it
Lows around 29°F — thermals are the difference between a walk and a march.
Why
Philadelphia in December averages highs of 45°F, lows of 29°F, 10 rainy days.
That climate means thermal underwear earns its space in the bag. Lows around 29°F — thermals are the difference between a walk and a march.