A BNSF train passes underneath the First Street Bridge in a light fog on Monday morning.

Heavy rains soaked Barstow Sunday night and then cleared out, said Brian Fuis, a spokesman for the National Weather Service out of Las Vegas. In order to have foggy conditions in the desert, there needs to be rain on the ground and light to no winds, as well as clear, cool conditions.

"The conditions have to be just right and they were this morning," said Fuis.

Exact figures for the occurrence of fog in the Barstow area were unavailable, but Fuis said fog is rare for Barstow because the area is normally windy.