It depends on what type of meter you are using incident/ ambient or reflective. Incident/ ambient meters measure the light by pointing it towards the camera. The relective meters are pointed at the subject as they record light which is reflected from the subject.
As you going to be working in the fog, this is a very flat even light source, so the two types of readings will give you similar results. I would over expose 1-2 stops to brighten up the sky. You may need a 400 ISO film as it will be quite dull.
No filters needed.
Wear a warm coat!!