I think it might have been yahoo answers(yes I'm a idiot for believing that website). And thinking about it, we play a lot of paintball and the only time the weather effects the co2 badly, is in the snow.Don't trust everything you read on the internet. Because the co2 is a gas, the pressure inside the sanister will change as temperature changes. The only thing this means is lower fps during cold weather and higher fps during hot weather. This will only change how fast the bb will get there, and shouldn't affect accuracy too much. In fact lower fps is a bit more accurate depending on the bucking. What website told you this?
Until, relatively, recently (in the UK at least) C02 was shooting way to hot to use for pistols.I never could understand why people use propane for airsoft. Just use CO2. You know what I use propane for? FIRE! (I am not a psychopath by the way)