Have you ever wondered what impact cloud cover has on temperatures?
Of course, during the day it is self explanatory, when we don’t have any clouds, all of the suns radiation (rays/ heat) is able to make it to the surface and warm us up, especially in the summer. During the winter, when you have snow cover some of the suns radiation will actually be reflected back out to space and while temperatures will be milder thanks to the sun, they will ultimately end up slightly cooler than they would have been had there been no snow on the ground.
On the other hand, when we have a mostly cloudy day, those clouds will not only reflect the suns radiation back to space but it will also absorb some of it as those rays try to make it down to the surface where we live. So, that means that less of the suns rays make it to the surface and ultimately, that keeps our daytime temperatures much lower than they would have been if we hadn’t had the clouds.
This process is reversed at night. In fact, on a clear calm night, that is when we will typically see our coldest nights. The warmth that was gained during the day will easily and quickly radiate right back out to space. We could easily drop several degrees right after sunset if we see clear skies and temperatures would continue to fall during the overnight period. If you add snow cover into the mix it can get even colder, especially if we are dealing with light to calm winds and/or a fresh fallen deep snow. Think back to the big Storm in December of 2020, the following night skies cleared, we had light winds and temperatures for many fell well below zero.
Now, on a night with clouds, you will not lose as much of the radiation that you gained during the daytime hours. Think of the cloud cover acting like a blanket, when you wear a blanket it holds the heat close to you and doesn’t let it escape, that is what the clouds do and they actually reradiate that “heat” back towards the surface. A night with clouds will typically end up around 5-10 degrees warmer than nights with no clouds.
So, ultimately, clouds really do play a big factor in temperature forecasting than you might think and that factor is typically more amplified at night.