I don’t think there is a yes or no answer to this. Everyone exercises differently and at their own pace for that matter. I usually tend to workout inside and running on the track in the SRC on campus. I haven’t yet developed a tendency to run out in the cold on a regular basis except maybe starting to as early as late March or early April. I think for my own body’s sake, I like to do more than just running around the track indoors because Its good to get your other muscles working like your arms for instance plus trying out new exercises for stretching. If I do start running outside it would be a gradual thing because the cold air is very high and can hurt your throat if you breath in too much. These are just some things to think about when continuing to run.