title_body: Will LiPo batteries deteriorate outside with the temperature changes due to day-night cycle?
upvoted_answer: The typical temperatures experienced across Europe shouldn't be a problem for LiPo storage; although depending on exactly where you are you may also want to check out this question: Do low temperatures damage LiPo batteries?
  
  If your storage location may be subject to direct sun then this could cause extra heating which may be harmful - think of a dark colour car on a hot day. Having a light (e.g. white) box or keeping it in shade would help here.
  
  Also, you do want to avoid condensation wherever possible as the moisture may cause corrosion or (if it pools/collects) may short the battery connectors. Many LiPo storage containers have vents to let pressure out if a battery fails and you don't want to seal these, so add the waterproof layer inside - something as simple as putting each battery in a zip-lock bag would work, for example.
  
  Finally, storing the batteries at the appropriate storage charge level will help maximise their life wherever you store them - see At what voltage per cell should I store a LiPo?