I play all year round, but I am 100% more of a summer player. Everyone calls me a fair weather airsofter because I don't like the wet (mostly the wet), and I'm not as keen on the cold. And then when the summer heat comes around the shoe is very much on the other foot and I start ridiculing them for being wimpy over a little bit of warmth as this country very rarely gets to temperatures that I can't play in. Usually has to be accompanied by high humidity.
However, I did used to play airsoft in the south of Spain. We'd have to stop game days there at lunch time during the summer because that was simply too warm to play. However, too warm being "hey, it's almost 40 celcius" instead of "it's just over 20 celcius"