Hay guys

I'm a first timer at one of these blow outs, so how do we dress for this? Don't know what to expect as far as weather, bull sh-- meeting, wet T shirt or what. No, what is the weather like up there this time of the year? Here we wear shorts and a T until xmas or almost anyway. Do we bring something to the cook out like some kind of a side or not? Is there a list of people that are coming? See what happens when you invite the new guy, he don't know sh--.