The lithium powder inside the battery cells decreases its electrical resistance as it warms up. This means that in warmer conditions your battery will discharge more quickly and will need charging more often.
You should notice that on cold days your bike will travel less far and this is due to this same property of lithium powder - its resistance increases with colder conditions. This means that you will travel further on warmer days.
A lithium battery is best stored in cold conditions where its internal resistance is greatest and will remain fully charged for longer. Camera batteries made of lithium are often recommended by manufacturers to be stored in the fridge to prolong their life. This isn't as easy with e-bike batteries! Store your e-bike battery in as cold a place as possible.
While storing batteries in cool conditions is good, always remember to warm the battery to room temperature before charging, charging from frozen can damage the battery.