Why Do I Need Sunscreen in the Winter?
Think light screen not sunscreen.
UVA is present 365 days a year through clouds, through window glass and car windshields. That little bit of daily damage is significant because it adds up over time in the skin as blotchiness, sagging, and lines.
Use a sunscreen daily. It should have 5-10% zinc or titanium or 3% mexoryl. If you live in a northern climate, get your Vitamin D level check or take 1,000 IU in the summer and 3,000 IU in the winter.