thermostats don’t run off what the temperature is outside.

usually, they have set points- heat comes on if the temperature goes below x, cooling/air conditioning comes on if it goes above y.

Does your system have a physical outside sensor for temperature? or is it pulling that information off the internet? your immediate location and how you’re situated on your property (plus things like how well your home is insulated, the color, how many windows you have… etc,) has more to do with how hot it gets inside. Or, for example, if you get a lot of sunlight coming in, it can heat up the house with it being horribly cold outside.

Regardless, if it’s not staying comfortable, look for a “heat and cool” option and then adjust the set points to within a more comfortable range. keep in mind that will cause energy costs to go up as it’s now actively heating or cooling more. (This time of year plays merry hell with HVAC systems,)