Cloudy Skies Limit Temperature Range During the Day

The sun has been absent for nearly a week now in northern Illinois, and the next couple of days don't hold much promise for seeing the big bright spot in the sky. Despite the lack of sun, temperatures have actually been above average, both during the day and at night.

Cloud cover acts like a blanket in the sky, limiting the amount of sunlight getting to the earth during the day but also limiting the amount of heat that is released at night. This has kept the high and low temperature the past week within a handful of degrees of each other, or limiting the 'diurnal temperature range'. The 'diurnal temperature range' is the difference between the high and low temperature. During the day, the sun's light is reflected back out to space limiting how far temperatures are able to warm, while holding whatever heat was built up during the day in at night. Little change in the forecast is expected Thursday, Friday and Saturday but a break in the cloud cover may arrive Sunday with a more mild Pacific air mass.