Tire Pressure light on my car won't turn off!

I have a friend that has a Ford Escape hybrid and has the same problem with the tire pressure light going on in cold weather. I have a Black and Decker air station that probably cost $35 to $40 that I use to maintain the air pressure in my tires. It’s easy to use. It does have a built in gauge, but I don’t think it is as accurate as a good $10 dial gauge that I have.