Rigga ........ been there, done that .....
Glorious fortnight summer holiday Italian beaches, all six of us packed into the VX 2300 at 0500 to drive north over the Alps to JHQ. As you say, summer gear on.
Stopping for a necessary pee at the top of the St Bernard Pass [I believe it was there] was no joke in a blizzard, but we managed to perform with great ease!
My eldest: "dad is supposed to know about these weather thingies ........."
Dad was as cold and misearable as any.