A moderate or strong La Niña like the one currently underway typically produces a drier than normal weather pattern across the southern United States, including much of the winter wheat belt in the Plains, reports MDA EarthSat/CropCAST. This dryness can have a negative impact on winter wheat yields, as it most often occurs during the two critical development periods, the first of which is the fall germination and establishment period. "Since mid-September, a pattern similar to previous moderate/strong La Niña years has evolved, with dryness occurring across eastern Colorado, western Kansas, Oklahoma, and Texas,” says Kyle Tapley, agricultural meteorologist with the company. “The dry weather has stressed germination of the wheat crop and may lead to poor establishment."
Following moderate/strong La Niña events, dryness is frequently found across Nebraska, western Kansas, Colorado, and Texas during the critical heading period in April and May, when moisture needs are greatest. "The combination of poor establishment and stress during heading results in reduced yields," Tapley explains. "Looking back at the 10 moderate or strong La Niña events since 1950, winter wheat yields were down on average nearly 3% nationally compared to the trend yield." The biggest departures were in Kansas, Colorado, Oklahoma, and Texas, where yields were 8% to 15% below trend on average.