What's with the weather?

I can't believe it's the beginning of January and the weather is so mild. Yesterday I was in the garden and I saw a butterfly, a bumble bee and in the evening I heard a hedgehog shuffling around. I've just had a little nose on the internet as I was worried that they should all be hibernating and it seems that the butterfly and hedgehog can wake on milder days during hibernation but will go back to sleep but I'm not so sure about the poor bumblebee, it seems like they can withstand colder temperatures than some other bees as they have those little fluffy bodies but I don't know what happens if they wake early, I'm just hoping she's gone back to sleep.