HPA

HPA will be consistent for any weather that will ever be tolerable to play paintball in.

It won't affect it at all, with a resonably full tank.

The reason is that the pressure inside the tank is proportional to the temperature of the gas. So lets say originally your inside pressure is 4500 at room temp (298 K). So when the temp drops to 0°F / -18°C / 255K, your pressure will be 86% of the original (ratio of temps).

So your internal pressure will be 3870 PSI. Then your reg takes it down to 850 for the gun.

So either way, the temp inside the tank is a lot more than the gun takes, so the reg will do it's job and you'll still have a constant supply of air.

And I still hate posting after BlueMunky because of his rather disturbing and oversized signature...

Later

blue orchids wrote: i know HPA isnt affected by weather but does that count for really cold weather like below 0? will that kind of temperature effect performance?

   

In your first sentance you answered your  own question .

The air itself will be fine - but your equipment will have other problems at that temperature.  O-rings start leaking, paintballs get fragile, lube/oil starts congealing...