With record warmth visiting the D.C. area this week, now is a good time to revisit the ongoing imbalance we’ve seen between very warm and very cold temperatures.

That imbalance is massive, and it’s growing.

Three years ago, I wrote that the number of daily record highs was outnumbering record lows by a 7 to 1 ratio since the year 2000. Even after the harsh “polar vortex” winters of 2014 and 2015, this pattern hasn’t significantly changed.

Records for daily high temperatures are now outpacing record lows by an 8 to 1 ratio since the year 2000, and more than 16 to 1 since the year 2010. These ratios are far higher than any decade before the 21st century — including the warm 1930s.

Statistically speaking, we would expect a comparable number of warm and cold temperature records over time. Instead, rising temperatures caused by greenhouse gas emissions and urbanization are greatly tipping the scales toward record warmth — a pattern we’ve seen not just locally, but nationally as well.

Since 2010, Reagan National Airport — D.C.’s official weather station — has logged 115 records for either warmest daily (afternoon) high or (overnight) low temperature. That’s 16.4 times the number of daily cold records (defined as either the coldest maximum or minimum temperature).

If we consider only the record high maximum and record low minimum temperatures, the ratio more than doubles (35 to 1), as shown in the chart below. Notably, in February 2015, D.C. finally set a daily record low temperature for the first time this decade. Apart from this, most of D.C.’s daily cold records from the early 20th century remain intact.


Source: Justin Grieser, The Washington Post