Do snakes hibernate during certain times a year?

Most snakes don't hibernate, it's only the ones that live outside of the tropics, and that is because of several reasons the most important of which are:

a) food - their prey may be more or less abundant are certain times of the year and

b) outside temperature - because snakes are ectothermic, the majority of their body heat is controlled by the outside temperature. In the tropics, snakes (and indeed, other "cold-blooded" organisms) don't need to hibernate, because they have a perfectly comfortable stable temperature all year. But in Europe/North America for example, these cold-blooded organisms will find it very hard to catch prey in cold seasons (so, winter) because they have very little energy to move and digest with!