As winter ends, change your focus away from working out to a diet that contains as little saturated fat, processed sugars, processed carbs and other processed foods as possible. Focus on cutting the fat instead of building muscles.
That's how you leverage winter for building six pack abs. Use it to really focus on building your abdominal muscles, without worrying about how you look. Then cut back on your tummy fat when winter ends to get visible, sexy abs by summertime.