Insider Blog: Why fog is more common into fall

You may notice more foggy mornings as conditions cool and we head into the new season. This is typically the time of year with the best setup for fog overnight, especially near bodies of water. On a calm fall night heat is able to rise from the ground quickly, leaving behind cooler, moist air at the surface. If temperatures drop low enough to the dewpoint, condensation and fog development are possible. Over water, which can hold heat much better, the temperature and moisture difference is much greater, leading to denser fog near rivers and lakes.

These conditions are set to change in a warming climate, as overnight temperatures in particular have seen a sharp uptick in recent decades. This may make it harder to cool to the dewpoint and saturate overnight, which could lead to less foggy mornings. Still, plan for extra time on the morning commute in the coming months as we see the best seasonal setup for foggy starts.