@ garfield: Brown snakes (Storeria dekayi) look a lot like a garter and are usually the first snakes out. Cold weather doesn't bother them. In fact, they prefer cool temperatures. Keeping them doesn't require heat and it should be avoided. Room temp is fine. This is a northern brown snake:



If that's what you have as long as it's not below freezing outside you could let it go and it will be fine. Doesn't matter if it's cold. They are sometimes active when there's still snow on the ground.