The U. S. Drought Monitor, released on September 6 places portions of southwestern and south central Minnesota in the Extreme Drought category (map at right). Many northwestern Minnesota counties, and many of Minnesota's southernmost counties are said to be in Severe Drought. In total, approximately 63 percent of Minnesota is considered to be in the Abnormally Dry category or worse.
Topsoil moisture across 69 percent of Minnesota's landscape is said to be Short or Very Short.
Stream flow measurements at reporting stations in the driest areas of the state rank below the 10th percentile when compared with historical data for the date.
Minnesota's drought situation is the result of abnormally dry weather over three distinct time periods (maps below). In some communities, precipitation deficits have amplified the drought situation during each of these spells of dry weather. In other communities, dry periods were interrupted by wet weather, only to have precipitation shortfalls degrade the situation yet again.
Here are the three drought scenarios:
The abnormally dry conditions in central and east central Minnesota developed rapidly during the month of August and during early September with many locations reporting less than one and one-half inch of rainfall.
The moisture deficits in southern Minnesota developed rapidly due to very hot and very dry conditions over the past twelve weeks. Over this period, rainfall totals in many Minnesota counties fell short of average by four or more inches. This is the climatological equivalent of missing an entire summer's month worth of precipitation. In some south central Minnesota communities, late-summer and early-autumn rainfall deficits are in excess of six inches.
The drought situation in northwest Minnesota, and also in far southeast Minnesota, is the result of an historically dry autumn in 2011, a snow-sparse winter, and a dry 2012 growing season.