year-round.
Even when it's 50 degrees and overcast (no joke). "Ninety percent of fine lines are caused by sun exposure, which makes sunscreen the ultimate anti-ager," says Doris Day, a dermatologist in New York City. Plus, your skin will be better hydrated, since UV rays also damage ceramides (good fats in the skin that prevent dryness). Get a tinted moisturizer with sunscreen—you can reapply it over your foundation without messing up your makeup and it'll actually make your skin look better. "I smooth it over my makeup before I go outside throughout the day," says Ellen Marmur, a dermatologist in New York City. Try La Roche-Posay Tinted Anthelios 50 Mineral Ultra Light Sunscreen Fluid or (Marmur's pick) Chanel Vitalumière