The climate of early 19th century Mississippi

Two outstanding weather records kept at Natchez, Mississippi from 1798 to 1819 are analyzed. In general, the climate appears distinctly cooler than modern values.

The average annual temperature for the era is 18°C, which is 1°C lower than 1961-90, and 0.5°C colder than 1884-1903, the coldest subsequent 20-year period of record.

The early 1810’s are remarkable for cold and wet conditions. Temperatures reached a nadir circa 1813, simultaneous with a well-marked wet period from 1812-1814. However, the famous “Year Without A Summer” of 1816 in New England was hot and dry in the Deep South.

Early 19th Century rainfall at Natchez averaged 84% of modern values. Wet (dry) periods occur inversely with warm (cold) periods.

Analysis of frost data imply a much shorter growing season. Some early autumnal and late vernal frost dates are unequaled in later years.

Methods of reduction, non-standard exposure, and limitations of the data are addressed.