Not necessarily. Depends on the climate. Here in the Sacramento Valley we have very hot, dry summers. In the fall and winter we get tule fog, which occurs when the damp ground warms up during the day, releasing water vapor into the air. At night, the air cools, the water vapor condenses into a very thick, low lying fog. A typical fall ride could be low 40sF (5-6C) and 100%RH.