For many residents of North America, the winter of 2013-14 has felt like one of the coldest in many years. Waves of Arctic air brought extended periods of cold weather and above-average snowfall to the middle and eastern portions of the United States and Canada. Seven Midwestern states had one of their top-ten coldest winters, and the Great Lakes were chilled until they reached nearly 91 percent ice cover. Even portions of Mexico and Central America were cooler than normal.
But human memory is not a scientific measure, and long-term perspective tends to get lost in everyday conversation and news coverage. The winter of 2013-14 followed two winters that were significantly warmer than the norm, which likely made this season feel worse than it was. Researchers at the U.S. National Climatic Data Center (NCDC) reported that the average temperature of the contiguous U.S. for the winter was just 0.4° Celsius (31.3° Fahrenheit), about 1°F below average.
Why was it only the 34th coldest winter in 119 years of records? Because most of the land west of the Rocky Mountains was warmer and drier than average, so those warmer temperatures offset the cold snaps to the east. California had its hottest winter on record, and several other states came close. Though it is not included in the contiguous U.S. measurements, Alaska also thawed in spring-like heat and rain that melted snow and ice.
The map above shows land surface temperature anomalies for North America for December 1, 2013, to February 28, 2014—the period known to scientists as meteorological winter in the Northern Hemisphere. Based on data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASAâ€™s Terra satellite, the map depicts temperatures for December 2013 to February 2014 compared to the 2000–2013 average for those months. Areas with warmer than average temperatures are shown in red; near-normal temperatures are white; and areas that were cooler than normal are blue. (Note: land surface temperatures are not the same as air temperatures, but they are a reasonable proxy for how warm or cold each region was. Learn more about the difference by reading this feature.)
The map below puts the North American winter in wider context. On a global scale, land temperatures for the December through February period were actually the tenth warmest in the modern record, according to NCDC, 0.87°C (1.57°F) above the 20th century average.
Far eastern Asia, particularly China and eastern Russia, were significantly warmer than normal. In Europe, Austria and The Netherlands observed the second warmest winters in their records, and Switzerland its third warmest. With temperatures as much as 5°C above normal, spring crops and plants began sprouting several weeks early across much of Europe. And in the southern summer, the extended heat waves in Australia and Argentina stand out.
NASA Earth Observatory images by Jesse Allen, using MODIS data from the Land Processes Distributed Active Archive Center (LPDAAC). Caption by Michael Carlowicz.