1:15 PM | The coldest December/January/February in 35 years for the contiguous U.S. and March is off to an amazingly cold start

[Niagara Falls has frozen over for the second time this winter; courtesy Reuters]

Discussion

December through February The 3-month winter period of December, January and February was the coldest in the last 35 years across the contiguous United States as measured by the U.S. Historical Climatology Network (USHCN). In fact, according to USHCN data, this was the 10th coldest 3-month winter period ever for the contiguous U.S. going back to the late 1800’s (below). The last time nationwide temperatures averaged this low in the December, January and February time frame was during the winter of 1978-1979 which happened to immediately follow two other very cold winters of 1976-1977 and 1977-1978. The cold weather this winter season has been the most dramatic “relative-to-normal” across the Great Lakes and Upper Midwest with some impressive results. For example, Chicago registered its 3rd coldest winter ever in the 3-month time period of December through February with the most days ever having its low temperature at or below zero. Additionally, the ice cover extent on the Great Lakes is at a record high for the month of March and quite close to the all-time record high. Finally, a rarity has occurred at Niagara Falls where the water has frozen over for a second time this winter season (above).

March The month of March has begun in much the same fashion as its three preceding months – namely, much colder-than-normal in much of the U.S. There have been numerous all-time record low temperatures set for the month of March that include the following:

-Atlantic City, New Jersey at 2 degrees (3/4) -Dover, Delaware at 6 degrees (3/4) -Charlottesville, Virginia at 1 degrees (3/4) -Dulles Airport, Virginia at -1 degrees (3/4) -Baltimore, Maryland at 4 degrees (3/4) [this broke the March record that held for the city of Baltimore since 1873] -Kansas City, Missouri at -3 degrees (3/3)

In addition, the following locations have experienced their coldest days ever in the month of March (i.e., the coldest high temperature in March):

-Little Rock, Arkansas at 28 degrees (3/3) -International Falls, Minnesota at -9 degrees (3/1) -Erie, Pennsylvania at 9 degrees (3/3) -Kansas City, Missouri at 5 degrees (3/2)

Finally, the snow cover across the Lower 48 states according to NOAA's National Ice Center is at ~54% which is the highest level in 10 years at this late date in the winter season.

Detailed description of the USHCN data The United States Historical Climatology Network (USHCN) is a high-quality data set of daily and monthly records of basic meteorological variables from 1218 observing stations across the 48 contiguous United States. Daily data include observations of maximum and minimum temperature, precipitation amount, snowfall amount, and snow depth; monthly data consist of monthly-averaged maximum, minimum, and mean temperature and total monthly precipitation. Most of these stations are U.S. Cooperative Observing Network stations located generally in rural locations, while some are National Weather Service First-Order stations that are often located in more urbanized environments. The USHCN has been developed over the years at the National Oceanic and Atmospheric Administration's (NOAA) National Climatic Data Center (NCDC) to assist in the detection of regional climate change. Furthermore, it has been widely used in analyzing U.S. climate. The period of record varies for each station. USHCN stations were chosen using a number of criteria including length of record, percent of missing data, number of station moves and other station changes that may affect data homogeneity, and resulting network spatial coverage.