The problem is it's the coldest night in about 30 years.

Here in Austin, it's just past midnight, and it's already down to 13°F (-10.5°C). It hasn't been that cold here since December 23, 1989.

Also, a lot of Texas homes have electric heat (except in the northern part of the state). Winters are relatively short and mild.

Many homes use electric heat pumps as the heating source. They're energy-efficient and easy to install in a home which has AC, so generally a good choice. But they get less and less effective as the outside temperature drops, so a backup electric heating coil kicks in, which uses way more electricity.