it may be that when you start off on a cool morning that one or more tires have significantly lower pressure than they should have, or have pressures that vary quite a bit from the other tires. as the tires heat up a bit from driving, the tire pressures increase and the light will typically go off.

first, try checking your tire pressures when the tires are cool. make sure they are set to the correct pressure. tire pressures increase by roughly 1 psi for every 10 deg F increase in temp. your morning temps in sacramento might be less than 60F in the morning but rise to 100F or more in the afternoon. if your tire pressures are say 32 psi on a hot afternoon when your car has been sitting, you might expect tire pressures to drop to as little as 26 psi overnight. tire pressures in that range or below will set off the low pressure indicator. make sure your tire pressures are adjusted to the recommended values in the morning or at night after the car has been sitting for at least an hour.