When it comes to U.S. weather, March is a notoriously fickle month. But even by March's capricious standards, the cold and snowy weather so far has been unusual, and when compared to the scorchingly hot March of 2012, it's difficult to remember that this is even the same calendar month.
Two years ago at this time, the U.S. was experiencing one of its most unusual heat waves on record, as temperatures soared to summer-like levels all the way to the Canadian border, and remained stuck there for weeks.
See also: In Parts of U.S., March Is the Coldest It's Been Since the 1800s
Fast forward to today, and the lower 48 states east of the Colorado Rockies are dealing with unusually cold and snowy weather, with temperatures more typical of January than March. New York City was struggling to reach the freezing mark on Monday, after a snowstorm missed the city by hitting areas to the south, which is not a typical development for this time of year. Washington, D.C. picked up 7.2 inches of snow on Sunday into Monday, which was its third-largest snowstorm on record for so late in the season. Weather records began there in 1888.

Computer-model projection for how the weather pattern aloft will compare to average as of the end of March, showing much below-average temperatures across the Midwest and Northeast.
Image: Weatherbell.com
So far this March, the continental U.S. has seen far more cold-temperature records than warm ones, which is a dramatic reversal from recent years, and a staggeringly different outcome compared to March 2012. During the past 30 days, there have been 3,037 record-cold daytime high temperatures set or tied in the lower 48 states, compared to just 760 record-warm high temperatures set or tied, according to the National Climatic Data Center.
There have also been 2,191 records set or tied for the coldest overnight low temperature, about 1,000 more than the records for the highest overnight low temperature. Most of the warm temperature records set this month have been across the west, which is a pattern that has existed for months.
In March 2012, the ratio of record highs to record lows was a staggeringly lopsided 17 to 1.
In Chicago, eight days reached or exceeded 80 degrees Fahrenheit during March of 2012. So far this month, the highest temperature Chicago has managed to eek out has been 53 degrees Fahrenheit.
This March has been unusually cold. And the cold is not done yet, either — far from it. Computer-model projections for the remainder of this month are advertising a continued cold and stormy weather pattern east of the Rockies, with multiple opportunities for more snow to fall from the Midwest to the Mid-Atlantic and Northeast, and temperatures averaging at least five to 10 degrees below average for this time of year.

Temperature departures from average for March 23 to 27, 2014.
Image: NOAA.
These cold-air outbreaks may continue to depress sectors of the U.S. economy, which took a major hit during the 2013-14 winter season, and could interfere with the planting of crops in northern agricultural states, particularly those around the frozen Great Lakes. Sea ice on the Great Lakes hit its second-highest level on record this year, after several years with well-below-average ice coverage.
The weather pattern that has dominated the U.S. for much of this winter has featured a dip in the jet stream, also known as a trough, across the Midwest and East, which has brought cold air southward from Canada. In March of 2012, the situation was just the opposite, with a massive northward bulge, or ridge, in the jet stream that pulled warm air from the Gulf of Mexico, and spread it all the way to Minnesota and Maine.
During March 2012, more than 7,000 daily record-high temperatures were set or tied, and a nearly equal amount of record-warm overnight low temperatures were reached. Dozens of all-time monthly high temperature records were set or tied, along with all-time records for the highest overnight low temperature.
The heat helped jump-start a devastating drought across the Great Plains, drying out farmers' fields so rapidly that scientists referred to it as a "flash drought."

Temperature departures from average in March 2012.
Image: Midwest Regional Climate Center
Long-term climate change may have made the March 2012 heat wave more likely to occur and more intense than it otherwise would have been, as it has with other heat waves. However, it's still an open question in the weather- and climate-science communities as to whether global warming is influencing weather patterns in ways that can cause colder-than-average conditions for extended periods of time in some areas. The short answer is: We simply don't know yet, but that's not the same thing as knowing that this isn't happening.
One thing that's clear is that many people tired of winter weather are probably wishing the weather from March 2012 would make a return visit sometime sooner rather than later. Unfortunately, they may have to wait until May.
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