What is the driving like in January from Athens to Olympia? Looks like mountainous terrain. Snow covered?
At Olympia, it rarely snows, and the roads are easily accessible.
Even all the way from Athens to Olympia, you won't encounter snow-covered roads.
Looking at a map is useful research. It shows a "rim Road" Running West from Corinith & all down the West side of the Peloponnese peninsula, along the shore, a modern level road. Maps can answer many questions.