Dry Summer 2008 (updated August 29, 2008)
Abrupt changes in precipitation patterns over time are common in Minnesota. This was the case during the 2008 growing season. A stretch of very dry weather arrived immediately on the heels of an extremely wet first half of June.
For the ten-week period during the last two weeks of June and into late-August, many Minnesota communities received less than four inches of rainfall. This came at a time of year when rainfall rates average roughly one inch per week. Thus, rainfall deficits over the ten-week dry spell topped four inches in many areas. Described another way, ten-week rainfall totals were less than 50 percent of normal for the period. When compared with the same ten-week time span in previous years, 2008 growing season rainfall ranked below the 5th percentile (one year in twenty) in many locales (see maps below).
Temperatures over the ten-week period were very close to historical averages. Days with temperatures in the 90 were relatively rare. This kept evaporative demand near seasonal norms and mitigated the situation somewhat.
As of August 26, the U.S. Drought Monitor classified nearly all of Minnesota as D0 - Abnormally Dry (see map at right). Significant portions of the state were placed in the D1 - Moderate Drought category.
Previous week's weather:
The weekly rainfall map for August 19 through August 25 depicted another dry week across much of Minnesota. The only significant rain for the week was found in far northwestern Minnesota where weekly precipitation totals topped one inch. Temperatures were two to four degrees above the seasonal average for the week. As was the case much of the summer, relatively few 90-degree temperatures were reported.
- Agriculture - The Agricultural Statistics Service reported that as of August 22, topsoil moisture across 56 percent of Minnesota's landscape was "Short" or "Very Short". This was a 15 percent deterioration from the previous week. Some of the driest topsoil conditions were found in central and north central Minnesota. Fortunately, stored moisture found lower in the soil profile supported reasonably good crop conditions into late August in many areas. In the August 25 Crop Progress and Condition Report, 62 percent of corn and 65 percent of soybeans were rated in good or excellent condition.
- Stream flow - Late August stream discharge in Minnesota rivers and streams was highly variable. Many Minnesota streams reported flows that were below the 25th percentile in the historical distribution for late August. In some northeastern Minnesota rivers, flows ranked below the 10th percentile for late August. By contrast, the Red River and many of its tributaries reported near-median flows in response to heavy rains that fell earlier in August.
- Wildfire Danger - The Department of Natural Resources - Division of Forestry classified late-August wildfire danger as Very High across the northern one third of Minnesota. Fire danger was rated as High across most of the middle third of the state.