BOULDER, Colo. — A measurement of the atmosphere above Denver on Monday recorded the driest air ever recorded in the month of December.

Colorado has a dry climate, and December is one of our driest months on average, but The National Weather Service in Boulder said a rare ‘stratospheric intrusion’ caused the record dryness.

A precipitable water measurement of .02 inches was taken by a weather balloon sensor on Monday morning. Not only was that a record for December, but was only .01 inches away from breaking the all-time driest record for Denver.

Precipitable water is a metric used to show how must moisture would come out of the atmosphere, if we were somehow able to squeeze out the entire column of water.

An average measurement for mid-December is about .2 inches, which is ten times greater than Monday.

The National Weather Service said this dry air came from high in the atmosphere where moisture is scarce. It’s called stratospheric intrusion.

“The entire stratosphere had compressed down, and we were getting this intrusion of stratospheric air right down, almost to the surface on the east side of the mountains,” said Meteorologist Mike Baker, with the National Weather Service. “It was just amazing to see that coming down.”

The cold winter months will normally cause the atmosphere to compress, but we rarely see cases this extreme.

Your body probably felt the dryness on the skin, nose, and eyes. Baker compared it to the sickness that tourists get when they come from a more humid sea level and go straight up to the slopes.

“First I’m craving oxygen, and the next thing they start craving moisture, and your brain starts to react to that and you get these terrible headaches. That’s Rocky Mountain Sickness,” said Baker.

Tuesday mornings precipitable water was .16 inches, and Wednesday mornings was .12 inches. Wednesday evenings cold front will boost moisture just a tad in the Denver area, but the next 6 to 10 days are expected to remain drier than average.