The winter-minus-summer daily peak score was 95 mm lower at The Battery than at Sewells Point in 1960-2024

We tested whether the known daily peak shape difference between The Battery and Sewells Point changes between October-March and April-September. We used NOAA daily hourly maxima in retained 1960-2024 records. A symmetric seven-day rule selected peaks above calendar-month 95th percentiles after monthly mean removal. The shape score is level one day after minus one day before a peak. The primary contrast is the winter-minus-summer score at The Battery minus the same difference at Sewells Point. It was -95.48 mm, with a conditional 95% three-year block interval of -151.18 to -34.95 mm. The interval supports a seasonal difference under this test. This targeted follow-up uses sites selected from a published campaign result. Daily sampling, tides, selected gauges, missing records, fixed event labels, and long climate cycles limit inference. The package provides source hashes, daily evidence, event rows, code, bootstrap weights, checks, and offline repeat instructions.

sea level · seasonal interaction · peak shape · NOAA CO-OPS · daily maxima