When I was despatch riding, I remember going out at -10C without the chill factor.
Originally, I had no fairing or screen, but relented later on and got a screen and some handlebar muffs. Found that the muffs blew into the clutch and brake levers at speed (XS750), so adapted some motocross hand protectors and put the muffs over the top of them - worked a treat.
Biggest day was a double trip to London, on a Friday, bucketing it down with rain. Had already been from Birmingham to Heathrow via Leicester. Got back to the office at about 4.30 pm and was sent to a private address in South Norwood, London. Got stopped by the Police for undertaking and was threatened with a dangerous driving rap from the 'good cop, bad cop' routine. They let me off and I got back home at around 12.30am having covered around 550 odd miles - I was very tired!
Prior to that, our family had a rural newsagents where the papers had to be delivered to farms, etc. If the papers came, you had to deliver. Ice, snow, rain, we had it all. The worst surface to ride a bike on (YB100) was when it snowed heavily, partially melted then refrozen after several farm vehicles had driven over it. It would then snow again on the ice leaving your teeth (sorry Berger) rattling in your mouth when you rode over it. That little YB100 was almost indestructable - superb little bike.