Daily Observation Records
Eight sets of manuscripts containing parts of Jefferson’s tables of daily meteorological observations have been identified. They make up Jefferson’s weather diaries from July 1776 to June 1826, with gaps and some duplication. Three of the manuscripts are in the Coolidge Collection of Thomas Jefferson Manuscripts at the Massachusetts Historical Society; others are in the collections of the Library of Congress, the Historical Society of Pennsylvania, the New-York Historical Society, and the New York Public Library; and one was in private hands when photostats were acquired by the Papers of Thomas Jefferson editorial project in 1947. Five of the records are in bound volumes that include other memoranda by Jefferson, such as financial accounts.
The daily observation records have been transcribed in full and constitute the primary body of data drawn on for searches and visualizations on this site.
For a detailed description, images, and transcription of any of these records, click on its image or label below.
Other Weather and Climate Documents
A second category of texts includes documents from Jefferson’s papers that relate to climate or weather but are not part of his ongoing register of daily observations.
Several of these texts have been extracted from the pages of the daily observation records. Some are notes Jefferson made regarding his observation procedures (for example, Note on “Rejected” Temperatures, ca. June 1799), and some record data from a period of time (such as Recapitulation of Depth of Snows, 1802–1803 to 1808–1809). Two of the documents record daily observation data but can best be understood apart from the main weather diaries. One of these is a table of observations from Jefferson’s voyage across the Atlantic in July 1784 on his way to France. The other document, labeled Bedroom Temperatures, 1802–1804, consists of columns of data that Jefferson incorporated into his observation record for a little more than a year beginning in December 1802. Those entries consist of readings from a thermometer placed in an unheated interior room, with notes of how far the room’s window was open overnight (not all of Jefferson’s notations in these entries are understood). Although he incorporated this data with his daily weather observations for the period, these entries really constitute a discrete set of experimental data.