CO2 in very cold temps is not that useful. You would want to warm the tank. Either keeping it a warm truck and putting blankets and towels around it when you use it or a warm bucket of water.
As for heat. The warmer the tank the higher the Pressure. At 88 degrees F the contents are 100% gas. Long as the tank was properly filled and not over filled it would require the tank temp to reach about 150-155 degrees to reach the 3000 psi which is what the burst disk is set at on most CO2 valves. At 122 or so degrees it should be around 2000 or so PSI.
So basically long as you keep it out of direct sunlight on extreme heat days and away from any extreme heat sources it should be ok. Also as you use/vent the tank its temp will drop dramatically.
If you are running in the desert when its 118 out and sunny I would make sure I had it inside something or a light colored cover over it.