A look at weather extremes and the big-picture climate connections.

2012 Has Had Most Extreme Weather On Record for U.S.

The first eight months of 2012 had the most extreme weather in U.S. since such record-keeping began in 1910, according to the National Climatic Data Center (NCDC). The Climate Extremes Index, or CEI, is used to track the highest and lowest 10 percent of extremes in temperature, precipitation, drought, and tropical storms and hurricanes across the lower 48 states. That the year-to-date was the most extreme on record should not come as much of a surprise, since the year to date was the hottest on record, and a massive drought, accompanied by searing heat waves, gripped much of the country from March through the end of the summer.

The Climate Extremes Index for the January through August period since 1910, showing the new record set in 2012. Click on the image to see a larger version.
Credit: NOAA/NCDC.

According to the NCDC, the extremes index was more than one and a half times the average value during the summer, which was the result of record heat and dryness. 

Studies show that global climate change is already increasing the odds of some extreme weather and climate events, particularly heat waves and precipitation extremes, including droughts and floods.

The CEI's value for the January-to-August period was a record 47 percent, meaning that 47 percent of the contiguous U.S. experienced top 10 percent extreme weather conditions. The average value during this period is just 20 percent.

"Extremes in warm daytime temperatures and warm nighttime temperatures contributed to the record high USCEI value," the NCDC stated in a report released on Monday.

The second most extreme CEI value on record occurred just last year. 

According to Jeff Masters of Weather Underground, so far this year 85 percent of the lower 48 states had maximum temperatures that were in the warmest 10 percent, and the percentage area of the U.S. affected by top 10 percent drought conditions was the 11th greatest since 1910.

Related coverage
U.S. Has Third-Warmest Summer, Year to Date
Ongoing Coverage of Historic Drought in U.S.
Hansen Study: Extreme Weather Tied to Climate Change

« Extreme Planet


By Barry Johnson (Cottontown)
on September 11th, 2012

Tell your weather man….........http://www.huffingtonpost.com/steve-valk/climate-change_b_1865683.html

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By Steve Goddard (Fort Collins CO 80526)
on September 12th, 2012

The climate was much more extreme during the 1930s, CEI is a complete joke.  It considers pleasant winter weather, like that on the east Coast last winter, to be extreme.

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By Otter
on September 13th, 2012

11th greatest? I’d be very interested in knowing what years comprise the top 10 greatest.

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By Andrew Freedman (Brooklyn, NY)
on September 13th, 2012


If you would read the description of the CEI, it says exactly what it includes and doesn’t include. The only way last winter’s weather would be in there would be if the temperatures/precip or other variables were in the top or bottom 10 percentile.

- Andrew

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By Guarionex Sandoval (Chicago, IL, 60615)
on September 14th, 2012

Geez. It would be helpful for readers to get the sense that you’re living in the same world. The heat this year was minor compared to the earlier half of the 20th century. The drought was less intense than that of 1988. Say, and did you hear of that thing called The Dust Bowl back in the first half of the 20th century? There were fewer tornadoes and hurricanes (continuing a long trend). The winter was mild (though preceded by 4 of the snowiest on record). There has been no global warming for 16 years, in fact, a slight cooling over that time. The 20th century warming was far less than that of the Medieval Warming period, which was less than that of the Roman Warming Period, which was less than the Holocene Maximum early in the current interglacial period, which was less than the previous 4 interglacial periods. We’ve had a 2000 year decline in global temperature to the present with periodic excursions in both directions along the way, and you’re saying stuff like,

“That the year-to-date was the most extreme on record should not come as much of a surprise, since the year to date was the hottest on record, and a massive drought, accompanied by searing heat waves, gripped much of the country from March through the end of the summer.”

Some of this temperature is due to Hansen fiddling with the raw temperature data to increase the more recent temperatures and to decrease those of the last century. The heat wave here in the U.S. was an ANOMALY. Look it up. Just like the heat waved that gripped Moscow and environs a few years ago was an ANOMALY, both of which were purely natural causes.

As far as old Jeff Masters is concerned: the number of all time heat records for the 1930s exceeded 60,000. For the 2000s, it was less than 40,000. And 1936 vastly exceeded 2012 in heat records. June 2012 was pretty much normal in temperature compared to the extremes of the last 40 years. Beginning in 1988, there were four years when temperatures for June were hotter than 2012.

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