We've had some questions about why frost occurs on some mornings, and not so much on others. Like why we didn't have frost on Monday morning, but we did this morning, Tuesday.

A frosted windshield is actually going to develop on a clear, calm night as opposed to a night when winter weather is moving into an area. Now, you can certainly have ice cover a windshield overnight, but that's a different weather phenomena. 

Here is what to look for, if you're wondering whether or not your car will have frost in the morning.

Are skies clearing? Can you see the stars? If you answered yes, this is one indicator.

How are the winds? Are they light, or is the forecast calling for gusty winds?

If there is a decent amount of wind ongoing, this creates mixing in the atmosphere and thus the less likelihood of frost developing. If the wind is calm, then the air is more stagnant and the temperature has a better chance of dropping to the dew point.

On Monday morning the air temperature dropped to 34 in Chattanooga, as opposed to 28 this morning. A wintry mix also brought 8-15 mph winds in the morning, as opposed to this morning. This morning, calm winds under 3 mph created a perfect environment for the temperature to drop close to the dew point which was 25-28 around sunrise Tuesday.

Here are quick ways to defrost that windshield early in the morning:

  1. Start the engine, and set to defrost if you have the option
  2. Use a plastic scraper or bristle brush. A metal scraper can scratch your windshield.
  3. Spray either lukewarm or cold water before wiping. Do not use hot water. Hot water will refreeze, and a salt or alcohol solution can ruin the integrity of the paint and wax on your vehicle. Your best bet is to use plain water.
  4. Don't leave your car running unattended!

Have a weather-related story idea? Feel free to email Meteorologist Brittany Beggs.