The 1957–1976 Summertime Drought Gap in the Southeastern United States

We examined drought frequency in the Southeastern United States, excluding Florida, from 1931–2024 to evaluate the frequency and occurrence of drought-free periods. Between 1957–1976, no summertime droughts occurred across most (i.e., 28 contiguous) of the 38 climate divisions, an event fivefold the next longest drought gap of four years during the study period. The 20-year drought gap was concurrent with below-average temperatures and absent dry conditions, and coincident with the core of the Southeastern “warming hole” and a negative phase of the Atlantic Multidecadal Oscillation (AMO). These conditions suggest that an unusual climatological event was the driver of the multi-decadal drought hiatus. Drought-free periods are critical for groundwater recharge, ecosystem health, water quality, agricultural productivity, air quality, and socioeconomic conditions, yet there is comparatively little focus in the literature on this topic. The spatiotemporal scale of the 1957–1976 drought gap is exceptional. The likelihood of a drought gap of this magnitude reoccurring approaches zero under current climatological conditions, suggesting a climatologically rare to potentially unique event occurred in the mid-20th century in the southeastern United States.