The ideal weather is whatever it's doing outside when you decide to use the smoker! Wind is really the only thing that will cause issues, and that's usually dealt with pretty easily by placement of the smoker. Just put it behind something to block the wind if it's causing problems.
You've gotten good advice as to what else to get, so I won't offer any more.
I will, however, offer a little insight into the way things work inside the murky depths of a guy's head. You mentioned "his buddy" smoked a bunch of meat, has a Weber smoker and that your boyfriend seemed interested in the whole concept. Kudos to you for noticing, by the way! This, however, raises a couple red flags. My mother, rest her soul, had four sons. To say there was a competitive environment in the house would be the understatement of the year. On those rare Christmases when none of us had been expelled, arrested, implicated or otherwise put on the naughty list and actually qualified to receive presents, we all got the exact same things. It got to the point that when we'd go shopping the salespeople would automatically ask, "will you be needing four of these?".
My rather long winded point is, guys mature to a certain point, roughly twelve years of age or so, and then stop. They see what another guy has, and if it interests them in the least, they want THAT. We don't grow out of this. Just ask my wife. We go visit a technophile friend of mine and she knows that within a day or two I'm going to start hinting that we need a new TV, stereo, computer or whatever new toy he has that I don't.
Getting your guy a smoker is an incredibly sweet gesture. Getting your guy a smoker that's inferior to his friend's is a minefield of hurt feelings, bruised egos and potential resentment. I'm not saying it makes sense, I'm just saying that's how guys are wired.
Now, what I would suggest, if at all possible, is that you return the smoker, get him the associated accessories (
charcoal chimney, thermometer, gloves, tongs etc...) and a gift certificate towards the smoker of HIS choice. Bear in mind, it's probably going to lead to a larger cash outlay, but it's an investment in preserving, for just a little bit longer, the illusion that his opinion and feelings matter in the grand scheme of things.