It has to be! Winter, Spring, Summer and Fall. If you care about skin health and keeping your skin vibrant, sunscreen must be in your daily routine!

Pick products suited for your skin type...for instance, if your skin is oily then choose a lightweight Sunscreen. SPF 30 does the trick. (There's a debate whether or not higher SPF's are better...but one thing is certain, it shouldn't be lower than SPF 30).
You likely won't need to moisturize before applying a sunscreen, but do give your skin an extra advantage by applying a facial Serum or facial tonic before your sunscreen. Research shows that antioxidants help protect skin from environmental damage.
Apply your Sunscreen liberally. Gently massage it into your skin until absorbed and give it about 15-20 minutes before you race out into the hot, sunny day.
The final step in your daily skin care routine is your Sunscreen. Also, products should be fragrance-free. Finally, pamper your skin after a long day with a gentle cleanser and feed and moisturize your skin as the last step in your evening routine.
Remember....any product you apply over a sunscreen will affect the protection it provides.

So, gently cleanse your face, apply your facial serum or tonic, then apply your Sunscreen.

(If your next step is makeup then it should include a sunscreen in the product).

Protecting your skin doesn't have to be complicated...keep it simple and enjoy the sunshine!