Pressure Temperature Density Loss
The table present on this page gives us an insight into how pressure is lost as the temperature decreases.

At 35-degrees Celsius or 95-degrees Farehnheit (AKA very warm/hot) our airguns running from High Pressure Air or HPA can be expected to perform very well because the air density has 0.025 units more of air.

However as we move down the chart to negative -25c/-13f, we can see the air has condensed considerably and when we pump our air guns, the air on the inside is no different to the air on the outside resulting in the tiniest, if any, burst of air.