I don't think you got what VillageIdiot (If anything an IR filter reduces the amount of green light you get. It is another piece of glass that the beam needs to pass through.

Now that's what only a mathematician and me would be pointing out, but I just had to say it.
And may I ask, since I'm new to this stuff but so excited, why do you think that a laser will have less power in a cold night? Shouldn't heat be a problem, and therefore cold conditions desirable?