Share

In Much Of U.S., Extreme Cold Is Becoming More Rare

Andrew Freedman
Published: January 8, 2014

The deep freeze that continues to affect the U.S. has resulted in numerous daily temperature records, and some all-time cold temperature records.

But in general, this Arctic outbreak, courtesy of a huge chunk of the polar vortex that the jet stream temporarily dislodged from the Arctic, is bringing the coldest temperatures in 20 to 30 years to many areas of the Midwest, Ohio Valley, Deep South, and the eastern seaboard.

Some of the most severe cold has affected the Midwest, from Minnesota to Illinois and east to Michigan. Chicago set a record for the 7th coldest noontime temperature since 1930, with a temperature of just -14°F at midday on Monday. But the city did not set any all-time cold records.

While the cold temperatures have been unusual and even deadly, climate data shows that intense cold such as this event is now occurring far less frequently in the continental U.S. than it used to.

Climate Central

The trend in frigid nights in St. Louis from the 1970s to the most recent decade. The yellow line in the graph above indicates the linear trend since 1970.

This is largely related to winter warming trends due to manmade global warming and natural climate variability.

Climate Central calculated the number of nights below a specific temperature threshold for dozens of U.S. cities based on the local climatology and current weather conditions.

The calculations encompass the entire winter season, and show that overall there is a downward trend in the number of extreme cold nights like we’re currently experiencing – although there are variations in a few cities.

This trend is consistent with climate studies showing that overall, winters across the contiguous U.S. have warmed by .61°F per decade since 1970, and every region has warmed at least somewhat over that time.

Winters have also warmed over a longer period of record, but the fastest warming has taken place during the past few decades. In addition, the fastest warming has taken place at night, rather than during the day, which is consistent with climate change projections.

Climate Central

The trend in frigid nights in Minneapolis-St. Paul from the 1970s to the most recent decade. The yellow line indicates the linear trend since 1970.

For example, in Minneapolis in the 1970s (1969-79), there were an average of 14.7 nights with temperatures below minus 10°F. But in the past decade (2002-2012), that number has fallen dramatically, to about 3.8.

The calculations run from July through June of the following year, so that we wouldn't break up the winter season.

In Detroit in the 1970s, there were an average of 7.9 nights with temperatures below zero degrees. But now, that number is closer to 2 nights. And in Washington D.C., the number of nights with a low of 20 or below was 13.5 in the 1970s, but was closer to 8.3 in the past decade. The overnight low at Reagan National Airport on Jan. 7 was 6°F.

And in St. Louis, the 1970s featured an average of 3.8 nights with a low of 0°F or below, yet in the past decade, the average for such frigid nights fell to zero.

A Climate Central analysis released in February 2013 found that the states with the coldest winters have been warming the fastest, including states hard hit by the current cold snap. The top 5 fastest-warming states, the analysis found, were Minnesota, North Dakota, Wisconsin, Vermont and South Dakota.

Climate Central

The trend in frigid nights in Detroit from the 1970s to the most recent decade. The yellow line indicates the linear trend since 1970

Beyond the U.S., the big picture which shows that global temperatures are on the rise. The rate of warming may have slowed over the last 15 years, but even so, each of those years was warmer than the 20th century average.

In fact, it has now been 345 consecutive months and counting where global average temperatures have been above the average for the last century (as of November, that is — numbers for December have not yet been finalized).

And there is ongoing research that suggests that rapid Arctic warming, which has been linked to human-caused global warming, may be creating more amplified weather patterns like the one that we are currently seeing, with sharp curves in the jet stream steering weather systems in unusual ways.

If that hypothesis is true, we could actually experience more extreme cold snaps, even as the planet continues to warm.

Related Content from Climate Central

MORE: Winter Storm Ion in Photos

The Chicago skyline and a freezing Lake Michigan are seen from the Museum Campus in Chicago on Sunday, Jan. 5, 2014. (AP Photo/Nam Y. Huh)


Featured Blogs

Pacific Northwest on Track for Warmest Summer on Record

By Christopher C. Burt
August 1, 2015

Another heat wave has engulfed much of the U.S. Pacific Northwest the past few days with Seattle, Washington now having observed eleven 90°+ temperatures so far this summer, an all-time record (9 such days in 1958 was the previous) and also July has been their warmest month ever observed. For some of the cities in the Northwest this has been the warmest June-July period ever measured and, barring a very cool August, will end up being the warmest climatological summer on record (June-August). Here are some details.

Guillermo Gathers Steam in NE Pacific; Invest 94L Clings to Life

By Dr. Jeff Masters
July 31, 2015

Hurricane Guillermo is stepping up its game in the Northeast Pacific, as it moves along a steady west-northwest course that could bring it near the Hawaiian Islands next week. In the Atlantic, Invest 94L shows little sign of strengthening, while in the Northwest Pacific, Tropical Storm Souledor could be approaching Japan as a strong typhoon next week.

PWS Service Interruption Update

By Shaun Tanner
June 16, 2015

The development team here at Weather Underground has been hard at work producing a new homepage! Please take a look at the sneak peek and tell us what you think!

Meteorological images of the year - 2014

By Stu Ostro
December 30, 2014

My 9th annual edition.

2013-14 - An Interesting Winter From A to Z

By Tom Niziol
May 15, 2014

It was a very interesting winter across a good part of the nation from the Rockies through the Plains to the Northeast. Let's break down the most significant winter storms on a month by month basis.

What the 5th IPCC Assessment Doesn't Include

By Angela Fritz
September 27, 2013

Melting permafrost has the potential to release an additional 1.5 trillion tons of carbon into the atmosphere, and could increase our global average temperature by 1.5°F in addition to our day-to-day human emissions. However, this effect is not included in the IPCC report issued Friday morning, which means the estimates of how Earth's climate will change are likely on the conservative side.