Double end bag changes due to Temperature?

[emeraldgsl]

I recently purchased a double end bag (https://www.titleboxing.com/punching-bags/double-end-bags/title-platinum-atomic-double-end-bag)
and noticed that it changes firmness in the day vs night. Is this normal? I have a speed bag as well and that does it too but it takes a long time of not using it to do so.

When it's hot out it feels fully inflated and when it's cold it feels like it need air, but is still usable.

Thanks.

 

[Championstuff]

Anything filled with air will be subjected to ambient pressure from heat and cooling.