Winter sea level and South Coast rain had a stronger adjusted link at San Francisco in 1993-2025 than in 1961-1992

We tested the difference between winter sea-level and California South Coast precipitation partial correlations in 1961-1992 and 1993-2025. Separate linear fits removed time and concurrent Nino 3.4 in each period. At San Francisco, correlation rose from 0.441 to 0.748 in 62 complete winters. The increase was 0.307, with a conditional 95% five-year block interval of 0.073 to 0.542. Three- and eight-year blocks retained positive intervals. Seattle had a change near zero, but the difference between site changes was uncertain: 0.313, with an interval of -0.147 to 0.678. The pair and split came from a prior descriptive result in the same data. These intervals do not correct for that selection and do not give independent confirmation. The result does not establish a physical cause, climate attribution, or a change in flood risk. Short records, missing months, model form, and resampling assumptions limit inference. The package gives source paths and hashes, preserved input fields, code, saved draws, figures, an independent audit, and an exact repeat.

sea level · precipitation · California · ENSO · correlation change · block bootstrap · exploratory analysis