One thing that can happen is the sudden availability of fluid water available to the plant. This doesn’t have to really “register” with a sensory process, or sense organ. When water is frozen, the plant can’t grow, when spring thaw arrives and the ice an snow melts, the plant can, and it does.
I’d heard, anecdotally, possibly in the New York Time’s Science Times, that buds form in late summer and are hidden by leaves, what we see in Autumn and winter may look big, but they’re not ready to open until Spring. Then again, as above, lots of liquid water may force buds to soften. The water has to go somewhere, and may swell buds.
Many plants (but not all) rely on photoperiod. The number of hours of sunlight causes changes that set off the blooming process. So maybe, even if plants have to soften their buds, they won’t be totally “fooled” by this warm winter and go into full bloom.