[souffle]

Hybrids can change colour and it does depend how much Winter white is in their genetic make up. Sometimes the genes are a bit mixed up and these little ones will constantly move back and forward between the shades. Even pure winter whites can do this. It's more governed by the light levels than the temperature. Some will even trigger a change in summer and go white. They tend to go almost fully white with a faint grey stripe gown the back. Summer coat would be the brownish coat all over with the paler belly. You can see when they start to change as they develop light eyebrows. I think your one will get darker and go fully brown and may change again as the light levels start to go up.