With all the coverage of the big winter storm sweeping the country, you’d think that the coming cold temperatures were unprecedented. And, for sure, it’s a big storm. And temperatures are going to drop a lot. Might even set some records, somewhere.
But we tend to lose sight of the modern context. Winter nights are much warmer now, on average, than they were just a few decades ago. In the Washington DC area, what we perceive as an outrageously cold night in the 2020s was merely a cold night in 1980s.
In fact, the main temperature impact of global warming is exactly that — warmer nights. And while you can’t infer global warming by looking at temperatures at a single point on the planet, you can remind residents of the DC area that winter low temperatures used to be much lower, on average, than they are today.
Here’s the official temperature data from Dulles International Airport, via NOAA. I’ve simply taken the lowest recorded temperature for each calendar year, and plotted that. (The 9 degrees for 2022 (so far) occurred back in January 2022).
Source: Analysis of weather data via NOAA.
Every year in the 1960s, 1970s, and 1980s had a lower minimum temperature than we are expecting from this super-storm. Almost every year in the 1990s, 2000s, and 2010s, ditto.
Similarly, we can check how common a low of 8F or lower was, back in the day. And the answer is, relatively common. For Dulles Airport, in the 1960s to 1980s, an average year had between seven and eight nights when the temperatures dipped to 8F or colder.
Source: Analysis of weather data via NOAA.
What was once a commonplace wintertime occurrence in this area — nighttime low of 8 or lower — is now a rare event.
When I was a kid, if it only got down to 8F around here, and only did that for a single night? That would have been reckoned as an exceptionally mild winter. But now, that single 8F night is the remarked-upon cold weather event of the year. Such is the slow and subtle impact of global warming.
The sheer area of this storm is unusual. It will be packing some strong winds.
But around here, the “Siberian” temperatures it brings, with all the associated news hype, would not have been at all unusual half-a-century ago. They only stand out in the context of the much warmer average nighttime temperatures that we currently experience. The chill from this storm hardly registers as a blip in the overall trend of rising temperatures.
