Clouds and Temperature

Did you know clouds have a big impact on temperatures and can often make or break a forecast? Cloudy conditions overnight will result in warmer low temperatures. Cloudy conditions during the day will result in cooler high temperatures. So what causes this?

Let’s look at how temperatures remain cool during the day under cloudy conditions. Clouds reflect about 20% of the sun’s heat back into space. This prevents 20% of the suns warmth to reach the surface, which can significantly impact temperatures. In addition to reflecting the heat, they also absorb around another 20% of solar radiation.

So how do clouds overnight make temperatures warmer than they would be on a clear night? Well, when there are clouds at night, they act as a thermal blanket. This prevents the heat from escaping Earth into space. The clouds absorb the remaining heat from the earth’s surface, and reflect it back down to the ground, making surface temperatures warmer.

Most of the time, weather models may not factor in cloud cover for their raw output of data. Thus, meteorologists must always look at the sky conditions that are forecast, then change their temperature forecast accordingly.