Normal, no but common, yes. It seems the neck has lower heat pain thresholds after severe whiplash. This means you respond more quickly to changes in temperature. Even a drop of one or two degrees can cause pain to increase dramatically. Then pain triggers a muscle spasm.
Researchers think the sensitivity to cold may be caused by injured nerve tissue. Some patients also have increased sensitivity to heat. If the skin temperature around the neck goes up, pain increases. These changes aren't found in patients with moderate whiplash injury. It's more common with patients who have severe neck pain and disability.
We don't know what to do about it yet, but more studies to understand what's happening are planned.