Why Can The Temps Drop 40 Degrees In The Desert?

I once said I'd explain why we can have a 30 or 40 degree swing in temperature within a 24 hr period.

It has to do with dew point and humidity.

Dew point: temp at which the air temperature must be cooled for water vapor to condense, forming water droplets, fog, or clouds.

Humidity: The amount of water vapor in the air, expressed as a percentage.

The sun comes out and heats up the air and the temperatures rise. That's why we have warm Winters and sometimes even hot Springs and Autumns. But when the sun goes down, during thse seasons, the lower the dew point (26 degrees tonight) and humidity (16% tonight) the greater the loss of heat into the atmosphere before the sun can recover the losses again.

In short, dry air is lighter and escapes!

One thing that can mitigate a rush of heat loss would be any cloud cover. That would act to hold some heat from completely escaping into the atmosphere, thus keeping the night a little warmer.

Perhaps you can see that trend on Thursday, Friday and Saturday (increasing cloudiness) then reverse on Sunday.

End of desert meteorology lesson. I hope you enjoyed it!