Precipitation data in Seoul, Korea during 1778-1907

Precipitation records from the 18th century were extracted from the digitization of ancient national documents. We provide improved data that removes errors and omissions from past research data January 2025: Duplicated dates (1786‑01‑01, 1786‑01‑02, 1786‑01‑03, and 1874‑01‑01) were deleted. April 2026: An automatic detection technique was applied to identify and correct rainfall events and precipitation amounts that had been missed or misspelled inadvertently. Although time‑series plots of the revised data are visually indistinguishable from the original datasets, statistical analysis reveals significant differences at 95% confidence level in monthly means for some months when evaluated using a two‑sample t‑test. April 2026: The letter “o” is used instead of the numeral “0” to distinguish trace values denoted as zero.