If you have a buried, well-top pressure tank as I do, do you have the pressure switch outdoors, on top of the well?  If so do you have a sealed, metal cover, outdoor type pressure switch or the plastic indoor style pressure switch mounted outdoors?  This plastic top switches get moisture in them and especially at the low temps we've had they go wonky. Also the 1/4" pipe the switch is mounted on may be filled with iron as shown above or ice.

If you replace the pressure switch make sure you open the hydrant nearby and let it run until it stops then close it before restarting with the new outdoor type pressure switch.  Or call a well guy or plumber to change the switch. Unfortunately many well people assume the pressure tank is indoors and only carry the plastic topped switches. Good luck.