The Impact of Extreme Weather on Winter Wheat: Evidence from the United States

Abstract

The impact of climate on winter wheat yields is analyzed across the United States, using county level data spanning from 1974 to 2023 for 25 states. Using county and time fixed effect models, we studied the effect of temperature and precipitation for the planting, growing and harvesting phases of winter wheat. By using standardized z-scores, the study measures the impact of extreme climate deviations on crop yield variability. Findings highlight that moderate temperatures and precipitation are beneficial for winter wheat growth. The extreme climatic conditions, especially extreme heat, cold and rainfall have a significant effect on yields. Warmer conditions during the planting season increase the yields but excessive heat during the planting and harvesting seasons reduces yield. Moderate rainfall increases crop production in all stages but extreme rainfall results in yield reductions. The analysis also found that excluding outlier counties in California and Washington did not significantly alter the signs of the estimated coefficients.Key words: extreme climate, winter wheat yield, Z-score