Counter to what other have said, I would argue it would make hardly any difference. Cold water will cool the system down more but you asked about putting out a fire which for the most part is just a matter of momentarily stopping oxidation (displacing oxygen). Technically hot water takes up a slightly greater volume and thus displaces a larger volume of air. If you took steam and blew on the fire it would put the fire out with a smaller amount of water than just cold liquid water. Unless the fire is something which can feed off heat to self-ignite (doesn't need spark) then my point stands.