no question. rain. until it is not the storm / thunderstorm type, as usually that cut off the electricity, so can't even play...
actually just having extreme hot in my area. daytime, you can't even go out, it is burning, the breathing is harder, can't focus as much as in cooler weather, even inside it is too hot and no cooler or climate machine can sort it out for more than few days.... and this is just the beginning of the summer..... (anyway, just 'waiting for' the first bigger thunderstorm, checking the weather gurus only try to decide which day shouldn't start to play, as even it is just near to us, the electricity, internet goes off, that's one of the most annoying thing, when you are deep in tourneys......)
good, that mostly i play in the nights, so it is a bit better.
anyway, yes night and/or rain season the neighboors rarely disturb, that's a good point, too.