Widespread improvements in Midwest and Plains; Hurricane Ida makes landfall in South

This U.S. Drought Monitor week saw widespread improvements across areas of the Midwest and eastern portions of the Central and Northern Plains states in response to beneficial rainfall. Rainfall accumulation in these areas ranged from 2 to 12+ inches leading to one-category improvements across areas of the Dakotas, Nebraska, Kansas, Iowa, Minnesota, and Wisconsin.

In the South, Hurricane Ida made landfall along the Gulf Coast of Louisiana on Sunday as a Category 4 hurricane with maximum sustained winds of 150 mph. The hurricane caused extensive infrastructure damage including widespread power outages in Louisiana and Mississippi, impacting more than 1 million homes and businesses as well as stranding residents amongst the floodwaters. In the West, dry conditions persisted across most of the region with approximately 90% of the region currently categorized as “in drought”. In California, two major wildfires (Dixie and Caldor fires) continued to intensify and expand due to the dry and windy conditions. In El Dorado County, California, the Caldor Fire continued to rapidly spread this week leading to the evacuation of residents in communities on the southern end of the Lake Tahoe Basin—including the City of South Lake Tahoe. In addition to impacting fire conditions, the on-going drought in California continues to strain the state’s water resources. This is reflected in the reservoir levels of California’s two largest reservoirs, Lake Shasta and Lake Oroville, which are currently at 43% and 34% of historical averages, respectively. In the Southwest, Lake Powell is currently 31% full and Lake Mead is 35% full. The total Lower Colorado system is at 40% full, according to the U.S. Bureau of Reclamation, compared to 50% full at the same time last year.


On Aug. 29, Hurricane Ida made landfall along the Louisiana coast as a Category 4 hurricane with maximum sustained wind of 150 mph. Hurricane Ida was the second most intense hurricane to impact the state of Louisiana, causing major widespread damage to infrastructure across the southeastern part of the state. Rainfall accumulations in the direct path of Ida ranged from 2 to 15+ inches with the heaviest accumulations observed along the coastal areas of southeastern Louisiana and Mississippi.

On this week’s map, drought-related conditions deteriorated in north-central as well as in the Oklahoma Panhandle where short-term dryness (past 30-day period) and reports of poor crop conditions led to the introduction of an area of Moderate Drought (D1). In the Texas Panhandle, precipitation deficits during the past 30- to-90-day period led to expansion of areas of Abnormally Dry (D0), while conditions improved to the south in the Big Bend region where precipitation has been above normal during the past month. According to NOAA NCEI, the May-July 2021 period was the 4th wettest on record in the South Climate Region and the 3rd and 5th wettest May-July period statewide for Texas and Louisiana, respectively.


On this week’s map, widespread one-category improvements were made across Iowa, Minnesota, and Wisconsin in response to beneficial rainfall accumulations observed during the past week with totals ranging from 2 to 12+ inches. The heaviest accumulations were observed across areas of northeast Iowa, where the 7-day average streamflow on the Cedar River at Janesville, Iowa was in the 99th percentile, according to the USGS. Elsewhere in the region, modest rainfall during the past week (1 to 2 inches) led to reductions in areas of Abnormally Dry (D0) in Illinois, Indiana, Kentucky, and Ohio. Average temperatures for the week were well above normal across most of the region (2 to 10+ deg F). According to the NOAA NCEI’s climatological rankings, the Upper Midwest Climate Region observed its 13th driest May-July period on record. At a statewide level, Minnesota observed its 2nd driest July and May-July on record. According to recent media reports, the dry conditions in northern Minnesota have been negatively impacting fish populations as well as wildlife and forest health.

High Plains

On this week’s map, areas of the region—including eastern portions of the Dakotas, Nebraska, and Kansas—saw widespread improvements in drought-stricken areas experiencing Exceptional Drought (D4), Extreme Drought (D3), Severe Drought (D2), and Moderate Drought (D1). The improvements were made in response to heavy rainfall during the past week (ranging from 2 to 5 inches) and minor improvements to soil moisture levels in some areas. Conversely, western portions of the Dakotas have continued to experience rainfall and soil moisture deficits which have severely impacted crops as well as pasture and rangeland conditions. According to the latest (Aug. 29) USDA North Dakota Crop Progress and Condition report, pasture and range conditions across the state were rated 61% very poor and 24% poor, while stock water supplies were rated 58% very short and 31% short. In terms of NOAA NCEI’s climatological rankings, North Dakota observed its 11th driest (-3.11-inch anomaly) May-July period as well as its 3rd driest (-7.40-inch anomaly) August-July period on record. Similarly, South Dakota had its driest (-3.17-inch anomaly) May-July on record as well as its 7th driest (-5.45-inch anomaly) August-July period on record.


Currently, ~90% of the West region (including Colorado and Wyoming) is categorized as “in drought” on the map with 54% in Extreme Drought (D3) or Exceptional Drought (D4). On this week’s map, some improvements were made in New Mexico and Utah in response to the cumulative impact of this summer’s active monsoon and its associated short-term improvements to vegetative health, soil moisture, and streamflow activity. Elsewhere, degradations were made on the map in the eastern plains of Montana, southeastern Wyoming, southern Idaho, and central Oregon. In Northern California, dry and windy conditions led to further expansion and intensification of the Dixie and Caldor fires during the past week. According to CalFire, the Dixie Fire is now the second largest wildfire in California history, while Caldor Fire is now the 15th largest. According to the National Interagency Coordination Center’s Incident Management Situation Report (Sept 1), the Dixie Fire had burned 819,956 acres (49% contained) and the Caldor Fire totals 199,632 acres (18% contained). During the past week, the Caldor Fire spread rapidly eastward up the Highway 50 corridor and into the Lake Tahoe Basin, leading to evacuation of the largest town in the basin—South Lake Tahoe. Looking at reservoir conditions across the region, statewide reservoir storage levels (August 1) were below normal across all the western states with the exception of Montana and Washington. In California, the state’s two largest reservoirs, Lake Shasta and Lake Oroville, were at 43% and 34% of historical averages on August 31, respectively. In the Colorado River Basin, Lake Mead is currently 35% full and Lake Powell is at 31% full (Aug. 31). On a positive note, this summer’s monsoonal rains have led to some modest reservoir inflows in the Salt and Verde River system reservoirs in Arizona where the total reservoir system was at 71% full (85% full one year ago) as of Aug. 31. For the week, rainfall activity (accumulations generally