Precipitation Deficits Increase Chances for Hot Extremes

Precipitation deficits can be an indicator of the number of hot days likely to occur in a region, according to a new study published in PNAS. The authors determine that in North America, the probability of an above-average number of hot days occurring in the hottest month of the year is over 60 percent if precipitation deficits—more specifically soil moisture deficits—have occurred beforehand, and over 70 percent for South America under the same conditions. The probability is below 40 percent if above-average wet conditions occurred beforehand in these regions. These new findings may increase the predictability of hot extremes in certain regions.