Annual dry-to-wet and wet-to-dry precipitation rates had no clear difference across 344 US divisions in 1901-2025

We test whether annual precipitation changes from dry to wet extremes more often than from wet to dry extremes. We use NOAA nClimDiv data for all 344 contiguous US climate divisions in 1901-2025. Dry and wet years use local full-record 20th and 80th percentiles. There were 1,470 dry-to-wet and 1,529 wet-to-dry transitions. The rate difference was -0.138 percentage points, with a conditional 95% five-edge block interval of -0.891 to +0.619 points. Whole national year fields reordered within 25-year periods gave no clear direction excess (two-sided p = 0.5560; 9,999 draws). A water-year check changed the small sign. All planned checks were uncertain. This is one precipitation-only annual metric. It does not measure water-store recovery, floods, a change over time, or a climate cause. The data, code, reference draws, audit, and offline repeat instructions are supplied.

precipitation · dry-to-wet transitions · direction · nClimDiv · uncertainty