In reply to Roberttaylor:
The Canon FD system. There are lots of A1, AE1progs, and such on ebay. T70 and T90 for electronic versions of those, which came later. I just looked at Ffordes and they not only have a lot of lenses but they have some 'new old stock' as well; kind of wish I wasn't into Nikon.
The Nikon FM will require you to change apertures with the aperture ring on the front, sometimes this is clumsy when wearing winter gloves. The Nikon F3 is heavy and it doesn't like damp cold environments IMO. F4 is super but too heavy.
Any SLR will probably do but as someone says above, one that offers programme mode will be more useful outdoors in my opinion, especially with an exposure lock for bright skies or ex. comp button for snow and water. I don't like to mess around too much in winter weather, just focus, exposure lock and shoot.
But I prefer point and shoot compacts outdoors, just like people do with digital. So an Olympus MJU2 or even an expensive Ricoh GR1, loaded with ASA 400 films like Tri-X for that 'feel' of analogue. A Canon power shot A1 waterproof camera works great with big glasses on. I have used an Olympus MJU in sub zero temperatures where the problem was the film getting brittle, not the camera (this camera is so small, you could take a digi compact as well for colour and back up).
Jon