My car's thermometer read 2°F when I got to Lake Dillon just before sunrise.
Over my thermal top, I put on a thin fleece, a fleece vest, the warmest down jacket I own, a neck gaiter, a ski mask, a beanie, snow boots, microspikes for traction, and drained the last of my hot coffee. It'd be overkill for skiing or snowshoeing, but hopefully warm enough for some landscape photography.
Driving in from Denver, I'd seen glimpses of fog over the lake, but in the dark it was hard to get a good feel for what the conditions might really be like. A few yards from the car, however, I saw the fog swirling above the lake below, just thick enough to be interesting without obscuring my view of the peaks in the distance.
Perfect! These are the conditions I always hope for on a shoot like this.