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5 Charts Help Illustrate 2012 As Warmest Year on Record

According to the National Oceanic and Atmospheric Administration (NOAA), 2012 was far and away the warmest year on record in the lower 48 states, beating 1998 by a full degree Fahrenheit.

These charts put that warmth into historical perspective for the country as a whole, and for a few select cities.

The 1°F margin between 2012 and 1998 may not seem like much at first, but usually such temperature records are set by just a few fractions of a degree. As seen in this NOAA chart, 2012 towers above the pack of warm years.

Temperature departures from average throughout 2012 as compared to the previous 5 warmest and 5 coolest years.
Click to enlarge the image. Credit: NOAA.

Every state in the continental U.S. had temperatures that were above average, and 19 states, from Utah to Massachusetts, had record warm annual average temperatures. In South Dakota, annual average temperatures were 4.4°F above average, putting 2012 in the top spot on the list of warmest years there.

A total of 45 states had annual average temperatures that ranked among their top 10 warmest on record. The three exceptions in the lower 48 were Georgia, which had its 11th-warmest year, Oregon, where 2012 was the 12th-warmest year, and Washington, which was the coldest state in the contiguous U.S. this year, with its 30th-warmest year. (Here is a list of the annual temperatures for each of the lower-48 states, as well as a Climate Central interactive on 2012 state temperatures.)

Statewide ranks of 2012 average temperatures. Any state marked "118" had its warmest year on record in 118 years of recordkeeping.
Credit: NOAA/NCDC.

NOAA’s National Climatic Data Center (NCDC) in Asheville, N.C., has a treasure trove of climate data, and on Tuesday they released a slew of city-by-city data  showing the extraordinary climate of 2012. Each state in the lower 48, except Washington, had at least one location experience its warmest year on record.

Des Moines, Iowa, wins the award for the largest gap between its average temperature during 2012 and the typical annual average. The average annual temperature was 50.9°F, which was 5.2°F above the 30-year average, according to the NCDC. The NCDC computed an “unusualness” score for each city that is based on the entire period of record for that station. In 2012, Des Moines had an average annual temperature that was 3.5 standard deviations from its historical average.

This chart, known as a Haywood Plot, shows the evolution of Des Moines temperatures during 2012 when compared to all other years on record.

The evolution of temperatures during 2012  in Des Moines, Iowa. As you read from left to right, a particular year's trace represents the average of all previous days during that year. For this reason, these plots are often very noisy early in a period (towards the left), but they provide an outstanding representation of unusualness over the whole of the period.
Click to enlarge the image. Credit: NOAA/NCDC.

Rochester, Minn., was another extremely warm location during 2012, having experienced an unprecedented March heat wave and a hot and humid summer. The average annual temperature there exceeded the average value by 4.9°F, or 3.4 standard deviations from its historical average, according to NCDC.

The evolution of temperatures during 2012 in Rochester, Minnesota. As you read from left to right, a particular year's trace represents the average of all previous days during that year. For this reason, these plots are often very noisy early in a period (towards the left), but they provide an outstanding representation of unusualness over the whole of the period.
Click to enlarge the image. Credit: NOAA/NCDC.

Omaha, Neb., was another one of the warmest locations this year, mired at the epicenter of the massive drought. The average annual temperature this year was 4.7°F above average, which was 3.1 standard deviations from its historical average, according to NCDC.

The year was also characterized by extreme drought, and two states — Nebraska and Wyoming — also had their driest year on record. Eight more states had annual precipitation totals that ranked in the bottom 10.

Average annual precipitation in Nebraska, showing the record dry conditions during 2012 (bottom right).
Click to enlarge the image. Credit: NOAA/NCDC.

At its maximum extent in July, drought conditions encompassed 61 percent of the nation, with the most intense conditions in the Great Plains, West, and Midwest. The nationally averaged annual precipitation total was 2.57 inches below average, making 2012 the 15th-driest year, and the driest year since 1988, which also featured a major drought.

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