With just more than three weeks left in the year, it’s virtually certain that 2012 will displace 1998 as the warmest year on record for the contiguous U.S. according to NOAA. The agency’s monthly State of the Climate Report, released on Thursday, shows that temperatures across the lower 48 states averaged 44.1°F for November -- 2.1°F higher than the 20th century average.
This means that while November, 2012, was only the 20th warmest November since modern record-keeping began (tied with 2004), it was still balmy enough to make the first 11 months of the year, from January through November, the warmest such period in NOAA’s record books.
November was also drier than normal, capping the 12th driest 11-month January-November period on record. That’s no surprise, since the worst drought to strike the nation since the 1950’s has stubbornly refused to loosen its grip on the nation, and in fact, has expanded slightly since October. The final U.S. Drought monitor report for November showed 62.7 percent of the contiguous U.S. experiencing moderate to exceptional drought, up 2.5 percentage points from the end of October.
Average rainfall (or the snowfall equivalent) was 1.19 inches across the contiguous states, 0.93 inch below the long-term average. That makes November the eight driest. For the autumn season so far, average precipitation was 5.71 inches, precisely 1 inch less than the 20th century average.
While drier-than-average conditions were seen across much of the lower 48, November’s relative warmth was skewed toward the mountain West, where Arizona, Colorado, New Mexico, Utah, and Wyoming saw temperatures in November among the top 10 warmest on record. In the East, temperatures were actually cooler than average; North Carolina, in particular, saw one of the 10 coolest Novembers on record.
It wasn’t just the averages that were unusual for the first 11 months of 2012, either: the U.S. Climate Extremes Index, which keeps track of extreme highs and lows in temperatures, precipitation, drought and tropical cyclones in the contiguous U.S., reported that the January-November period was the most extreme on record. Extremes in warm temperatures and in the area affected by drought were major contributors — although Superstorm Sandy and Hurricane Isaac surely played a role as well.