Three things on that. One is that most have heat pumps for air/heater, but in super cold, the heat pumps do not work well, and that is why they have a resistive element in the unit (think hairdryer) that turns on. Super inefficient to heat that way (but better than nothing). I believe there is more power draw on that, versus the heat pump on AC days.
Second, everyone is home in the state and cranking their electric. I have my three (upstairs, downstairs, garage) units set for 65 (62 at night), but am thinking many have them at 72.
Lastly, I got notice that all the west Texas wind turbines are shut down. Many frozen over. We get a bit of power from wind that isn't available right now. I bet many wish for a good old fashioned coal factory pumping right now