We drove in my car to the van hire depot with -4 degrees showing on the display!
We headed off into thick fog that didn't clear for about 60 miles/100km and as the road got higher there was more and more snow at the side. Crossing Beattock Summit (highest point on the trip) the display showed -9 degrees!
Only on the last 40 miles/60km or so of the trip did it brighten up and the temperature rise above freezing (just!)
We found the seller's house, David bought the bike, and we loaded it into the van for the trip back. Temperature was about the same, but at least the fog had cleared. We had a stop for coffee each way, and along with the time at the seller's house and returning the van, it took us about 8 hours all in.