North Texas tied a dew point record. But what the heck is a dew point?

Have you ever woken up to foggy windows in your car or house?

It’s swampy, muggy, steamy or, as one Twitter user in Frisco described it Thursday: “air you can wear.”

The reason for that sticky morning air is the dew point. Dew forms when the air can’t hold any more water vapor. The dew point is the temperature at which that occurs.

Midday Thursday, Dallas-Fort Worth the dew point tied a record 80 degrees. Including yesterday, the dew point has hit this record on five days since 1947 (when dew points started getting recorded), according to the National Weather Service.

The last time the area saw a dew point this high was in June 1997, according to WFAA Channel 8.

The higher the dew point, the stickier the air, and, consequently, the more miserable the residents of the Metroplex.

The National Weather Service describes the dew point as “comfortable” when it’s less than or equal to 55 degrees. A dew point greater than or equal to 65 degrees is “becoming oppressive.”

Can’t I just look at the humidity to see how humid a day will be?

Dew point heads know: the answer is no.

Relative humidity — which is shown as a percentage — is a measure of how saturated the air is compared to how much it can hold.

So, if the temperature is 55 degrees and the dew point is 55 degrees, the relative humidity is 100%.

But warmer air can old more water, so that’s why Thursday’s relative humidity of 73% with a temperature of 90 degrees felt so miserable.