Scott:
I have glassed a couple of boats in cold weather and there are a couple of things I have experienced:

1) Epoxy not adequately kicking. If the epoxy is too cold, it just doesn't seem to kick off the reaction. I used to keep my resin and hardener on a plastic covered heating pad while I was working. I also store my resin in a heated area. I found that mixing up a batch and then waiting until I could feel it starting to warm up ensured that the reaction was actually happening and I wasn't just spreadinging on very expensive honey.

2) Bubbles in the epoxy. I use a portable kerosene heater in my unheated garage when I am glassing. I found out the hard way that if you glass and the temperature continues to rise, bubbles will form. The best bet is to warm the space before and while you are glassing, then cut the heat while it is curing. That generally gets rid of the bubbles.

3) Really long cure times. I am working on a SurfYak right now that was driving my nuts trying to get the epoxy to cure. I ended up making a boat oven. I set up two saw horses and put the boat underneath. I then put 2x4s running across the two horses to create a frame. I threw a tarp over the whole thing and put my oil-filled electric heater underneath. Bake at 900 watts for two days and the boat is now cured.

There is no reason you cannot glass when it is cold, you just need to be aware of a couple of potential issues.

Regards,

Marcel