
This is my woad dress, which I made back when I was in the SCA and I dyed it with woad. This is made of nubby raw silk, which I have since discovered is not a period medieval fabric. It's awesome fabric, though!
As you can see, medieval clothing works in just about every situation. So far I have found that it is far superior to modern fashions. I have worn it in all kinds of weather, from cold Colorado nights to hot and muggy North Carolina days. I noticed on the hot days, that the gal with me, wearing a t-shirt, was sweating quite a bit, so I figured that I wasn't any hotter than she was, though I was wearing long sleeves and a long gown. The fabrics I use, the same used in the Middle Ages for the most part, are breathable, natural materials. So I feel the breezes on my arms through the fabric about as easily as if I were wearing a t-shirt. And I don't have to worry about sunburn!
The best thing is that I am almost always completely comfortable, temperature-wise. If it gets too chilly I first don my medieval hood (I have a red one and a green one, both shown above). It's amazing how when your shoulders and neck are covered how much warmer you feel. On occasion I'll put the hood up on my head, it has come in handy in the rain and when it was cold. I can also put on an extra layer if it's cold, or remove a layer and just wear my undergown if it's hot. I do have a gray woolen circle cloak, but I haven't yet needed that much.
Lots of times I've noticed friends and family around me suddenly get too cold, and I can't help but say, "If you were just wearing medieval clothing..."
Oh, and notice above how easy it was to go wading. Everyone else had to roll up pants-legs and they still got them wet! When I went horse-back riding, I simply wore long pants underneath my gown.