For frost to occur this time of year, you need more than just a cool air mass. You also need a clear sky, a light wind and dry soils also help the cause. Dry soils have more air pockets and more conductivity. The air near the ground is cooled by conduction, which is the air coming into contact with the ground. With dry soils cooling more rapidly as the sun goes down than does wet soils, the potential exists for overall cooler low temperatures. Although many areas did get some rain on Monday, it was mostly light and the top soil has or will be drying off quickly. This means some locations, especially in northern North Dakota may have frost potential in the next few mornings.