Since snakes are ectothermic (cold-blooded), they need to regulate their body temperature by external means and may find your yard ideal because of the sun or shade. For example, when it is hot, snakes hide in shaded places. During cool days, they sun themselves in open places.
Snakes cannot tolerate cold winter. Therefore, they hibernate in groups in dens, which can be holes in the ground, under rocks, concrete steps, slabs, patios, or in the foundations of buildings—or they make their way inside your home.
In spring, when temperatures are above 50°F, most snakes leave their over-wintering sites and move to hunting places.