I saw fog like that at half past three in the morning while driving home from the airport last month. It's nothing uncommon in the summer. Where those photos were taken it's perhaps even a little more common than in our neck of the woods because that place is at a somewhat higher elevation, further from the nearest coastline and also further north. Hence the cooler nights and the fact that it's a heavily forested and more sparsely populated region. Farmers lose their crops to night frost more frequently than here.