This may seem stupid but has this happened to you?

The pressure in my stock summer tires dropped to 26 psi and the alarm keep going off when it is really cold outside but would be ok when the temperature goes up ie. after parking the car in a warm garage for awhile. The psi will go back up to 37-38 psi when warm. I am not driving it when it's snowing but like to take it out when the roads are clean even when it's minus 20 degrees celsius. Maybe I just have to pump more air in when it's really cold...I am afraid the air will expand too much and the pressure is too high when it's warm again.

 

The same thing has happened to me twice, since the beginning of the year. I just made sure all 4 tires had the recommended psi in them. When the weather starts warming back up, I'll monitor the psi and make any needed adjustments.

 

Oh yes I've had this happen several times even here in the deep south. after the car has sat out in the weather for a little while the alarm is going off. The 1st time it did it I added more air, but now that it's warmed up I see that the psi's ok. As you said, as I drove a little, or parked in the garage, the psi went up, but the alarm stayed on.