depends. its gonna be bad if ur cells short on the chassis but this only happens when cells have cuts and nicks in shrink wrap.
if its hot and ur having probs with charging batterys and getting to hot then u prob need to put em in a cooler or sumthing.
i charge packs in my car and still use the temps sensor so ur pretty safe just be sensible dont charge at 8 amps lol.
to make Keith happy