This was my first visit to Crater Lake National Park and although it was May, there were still piles of snow along the side of the road that stood over 15 feet high. Driving next to these snow banks was enough to make the trip worthwhile and is a great reason to visit Crater Lake in the winter.
The big drawback to visiting Crater Lake in the winter is that your activities are limited. Crater Lake rim drive is closed. Due to the large amount of snow, hiking is pretty much out of the question (although cross country skiing and snow shoeing would be possible — permits are required for overnight snow camping). That means that there’s really only one spot to view and take photos of the lake:
As can be seen from the photos, the other big difference is that cloud covered weather doesn’t let the beautiful blue of Crater Lake shine through, and instead leaves it a steel grey. I heard that has a much bluer tint when the sun is shining brightly even in winter, but to really get the color you need to visit in summer (which means I will be back again) when you can take photos like this: