How unprecedented was the February 2021 Texas cold snap

Winter storm Uri brought severe cold to the southern United States in February 2021, causing a cascading failure of interdependent systems in Texas where infrastructure was not adequately prepared for such cold. In particular, the failure of interconnected energy systems reduced electricity supply just as heating demands spiked, leaving millions of Texans without heat or electricity, many for several days.This motivates the question: was the cold that contributed to this infrastructure failure a "black swan" that could not have been anticipated, or did historical storms provide a precedent? We compute the population weighted temperature excursion below 68°F as a proxy for heating demand and use this metric to answer the question "what would the aggregate demand for heating have been had historic cold snaps occurred today?". We find that local temperatures and the inferred demand for heating across the Texas Interconnect during a storm in December 1989 were more intense than those recorded during February 2021, and that several other storms in the modern era were comparable. Given anticipated population growth, future storms may lead to even greater infrastructure failures if adaptive investments are not made. Further,electricity system managers should anticipate that upward trends in electrification of heating may cause peak annual loads on the Texas Interconnect to occur during winter storms.