I had a frog sit an extra day because of a stupid mistake by the USPS, and it actually dropped down to around 50. When I got her, she was cold and lethargic... but after warming up she became active, alert, and hungry lol. Actually it was also a Sip tinc now that I think about it, maybe they have bad luck with shipping (just kidding of course). Hopefully yours will be fine, in general it is better to be cooler then warmer for darts and they will be inside... so it might not be really that cold for them. Good luck with them.