Climate warming decreases number of extremely cold winter days

For this cold season, we’ve already seen quite a few minimum temperatures below 0 degrees. In the northern latitudes and higher elevations, those lowest temperatures have occurred more frequently. But is this season’s number of very cold days anomalous?

The seasonal total is a bit below average. This latest event could get some of those stations closer to their average seasonal total. It’s likely that, for much of the Lower 48 states, this week will be the last time we see those temperatures until the next cold season.

While it may seem counterintuitive to talk about extremely cold temperatures in a warming climate, cold extremes can and will still occur. It’s something we need to continue to prepare for, as the subzero temperatures can result in significant impact on our bodies, infrastructure, animals and vegetation.

The National Oceanic and Atmospheric Administration updated its climate normals for US stations, based on observations for the 1991-2020 period. Climatologically, it’s normal for many stations to experience temperatures below zero every year.

Across the northern Great Plains and in the far northeast, it’s common to observe about 30 days of temperatures below zero. For some spots, including much of Alaska, there are about 60 days of temperatures below zero.

Unless you live around the southern reaches of the United States or along the Pacific Coast, the February average minimum temperatures are still in the teens and 20s for much of the country and even colder farther north. while the coldest month of the year is either December or January for the majority of locations, it’s still no surprise that we can get very cold outbreaks in February.

So, yes, during the winter, we can still get really cold. But that’s not to say climate change hasn’t had an impact on those colder temperatures.

Climate scientist Brian Brettschneider showed that most of the country is seeing an increasing trend in the lowest temperature observed each year, by an average of about 4.3 degrees.

Additionally, a recent update of State Climate Summaries has found that many states are experiencing a decreasing trend in the number of very cold nights, especially since the 1990s. Despite experiencing the most frequent number of extreme low temperatures, the decreasing trend in low temperatures is probably the most pronounced for Alaska. (If you’re interested in exploring more temperature statistics for your location, check out this interactive map of climate perspectives from the Southeast Regional Climate Center.)

While we can expect extremely low temperatures to intrude every winter, these events will continue to decrease as the climate continues to warm. That does not necessarily mean that cold temperatures will disappear completely — at least not in our lifetimes. Regardless of the changes in our climate experiences, it’s important to be prepared for the entire range of possibilities.

Becky Bolinger is the assistant state climatologist for Colorado and a research scientist at Colorado State University.

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