Pack or skip
Thermal underwear for Philadelphia in January
Verdict
Pack it
Lows around 25°F — thermals are the difference between a walk and a march.
Why
Philadelphia in January averages highs of 40°F, lows of 25°F, 9 rainy days.
That climate means thermal underwear earns its space in the bag. Lows around 25°F — thermals are the difference between a walk and a march.