Funny that this comes during a week where we've got rain forecast for the next 5 days and it's almost pitch black outside at 7pm.
No one is saying to stay out of the sun and live like vampires, but we have to realize that the intensity of the UVA/UVB rays reaching the surface of our planet is increasing due to the destruction of ozone. Sure, people can argue about the existence of that and global warming, but try getting an appointment with a dermatologist. Many of them are operating at maximum capacity dealing with clients with sun-induced skin issues.
If you don't want to take Vitamin D tablets (and I'm a huge fan of those), get your sunlight exposure before 10 am or after 4/5pm (during summer obviously), when the sun is not at its strongest. This is especially important for young kids. Doubly so for fair skinned, freckled and red headed individuals.
Apparently, all you need is 10 minutes a couple of times a week. (If you live in a northern country like Canada, you can probably see the problem with this already, and the need for supplementation)
I remember kids when I was young getting sunburns and having "contests" to see who could pull their skin off in the biggest sheet. What were we thinking? Clearly, we weren't.
You may find that you find winter easier to tolerate as a result of taking Vitamin D3. For many, their mood improves as does a number of other problems including, for me anyway... lower back pain.