Several reports this week helped illustrate the severity of the weather situation in the United States and its impact on agriculture. First, the National Climate Data Center declared 2012 as the warmest year on record for the continental United States. The same day, the USDA released its Weekly Weather and Crop Bulletin, showing the persistence of drought across much of the country this winter.

In related news, USDA also announced the listing of 597 counties for disaster assistance due to drought, the first such listing for 2013 coming just one week into the new year.

December started out unusually warm, with record-high temperatures recorded from Texas through the upper Midwest early in the month. A cooling trend moved across much of the country bringing much-needed precipitation to in some areas, and according to preliminary data from the National Climatic Data Center, the contiguous U.S. experienced its 10th-warmest, 20th-wettest December on record. But while some areas received above-average precipitation during December, others, particularly across Texas, Oklahoma, New Mexico and into Kansas saw less than half their normal precipitation for the month.

Within the USDA report, a drought outlook map from the National Oceanographic and Atmospheric Administration shows drought conditions likely to persist through March across most of the western two-thirds of the country. About 60 percent of the continental United States currently is under moderate drought or worse, according to the U.S. Drought Monitor.

As mentioned, Agriculture Secretary Tom Vilsack earlier this week listed 597 counties as disaster areas due to drought. The designation will provide access to low-interest loans for farmers in affected counties. Many of the counties listed are in the Plains region, including 88 in Kansas, 76 in Oklahoma and 157 in Texas. Read more about the disaster-area listings from USDA.

Conditions in the Plains region have caused a decline in the hard red winter wheat crop. By December 30, the portion of the Plains wheat rated in very poor to poor condition included 61 percent in Oklahoma, 49 percent in Nebraska, and 31 percent in Kansas.

Further east, the soft red winter wheat crop is doing better according to the USDA report, and as of December 30, 70 percent of the crop in Illinois was rated good to excellent.

Although December brought cooler weather to parts of the country, the persistence of drought and generally mild conditions look eerily similar to a year ago, when a mild winter and early spring led to what became the warmest year on record in the United States. The average temperature for the continental United States during 2012 was 55.32 degrees Fahrenheit, topping the previous record from 1998 by a full degree according to the National Climate Data Center (NCDC). According to an Associated Press article, year-to-year differences are more typically measured in tenths of a degree, and breaking the record by a full degree is unprecedented.

The NCDC will release its data on global temperatures for 2012 next week, but through the first 11 months of the year, the world was on pace for the eighth warmest year on record. Read more about the long list of heat records that fell last year.