Jesus, I have read through the various responses you've gotten, and IMO, they are ALL, without exception wrong! I bought my current puppy in March of 2017, which by the way, is one of the two snowyest months of the year in Colorado. My puppy had NEVER been inside a house until I brought her home. So 40s or even 30s mean absolutely nothing to a GSD puppy - unless they've always been inside and haven't been acclimated to the cold. And even then, if they have a house or kennel to snuggle up in, they're fine!
My own puppy almost couldn't be called in when temps went below zero F here, she seemed to just love it!
But keep it in mind, it's more about "drastic change in temps" than it is about current temps! If in doubt, watch or check on them frequently. I think you'll see that it takes temps much below 32 to make even a small puppy cold!
It's not the size of the dog in the fight, it's the size of the fight in the dog. Mark Twain