Hi Bluebean
The recommended weight for wild hogs is 450g to survive hibernation. (500g for one which has been in captivity, because it’s likely to lose a bit of weight on release) See link below. In addition, there is still time for the hog to put on more weight before it hibernates – if that is what it chooses to do. Especially if someone is supplementary feeding it where it’s released. It isn’t really officially autumn yet and the weather is still mild.
You will find the information in this link useful if you are going to be caring for and releasing hedgehogs: https://www.britishhedgehogs.org.uk/pdf/Hibernation-Weight.pdf
It’s also important, if you haven’t already, that you read: https://www.hedgehogstreet.org/guidance-on-releasing-rehabilitated-hedgehogs/
