Well, even though this is a desert, it still snowed a bit last winter. If BREW keeps you around for eight or nine more months, then you'll definitely get the chance.

[He's not sure if that 'together' of Kaworu's includes him. And he's certainly not going to ask. He's getting the idea that he wouldn't even want to go play in the snow with the two of them, even though it also sounds stupidly tempting, too.]

But your best bet is probably just going on a mission. There's usually at least one or two missions in mountainous areas where you're likely to run into some snow.