Well i put them in the garage in winter they seem just fine and will survive but i live in england so we have pretty cold winters but i have no idea how bad or cold it gets over there so ill have to pass, only been over there in summer. At the owl center we have had frozen water in bowls and after they have thawed out the bloodworm still are live, thisb is of course if only the top layer of water freezes not the whole thing.