Axolotls like temps roughly around 54-68°F so they do like cold water just not as cold as it would get in Canada. If I remember correctly they originate from a mountain lake in Mexico so it tends to be cooler there then the rest of Mexico but it still doesn't get anywhere near cold enough to freeze over. Also neat fact about axolotls is that if they lose a limb they can regrow it unlike many other amphibians. They are also unable to fully turn into a salamander unless they eat some of their own mucus so they can stay fully aquatic their entire lives potentially. Just don't confuse them for "water dogs" otherwise known as the tiger salamander, water dogs will become salamanders regardless.