The Jefferson Weather and Climate Records

<a href="https://jeffersonpapers.princeton.edu/author/alison-dolbier/" target="_self">Alison Dolbier</a> | October 02, 2023

An image of a manuscript from Jefferson’s weather record with his morning and afternoon observations at Monticello from January 1 through April 30, 1796

A page from Jefferson’s weather record with his morning and afternoon observations at Monticello from January 1 through April 30, 1796 (Library of Congress).

The history of Earth’s weather (conditions at a particular place and time) and climate (long term weather patterns and regional environments) is the basis of understanding modern climate trends and weather patterns. Evidence of past weather is found in fossils, ice cores, tree rings, sediments and other natural records that attest to seasonal conditions, catastrophic weather, geologic events, and weather trends. The private diaries, journals, academic papers, and almanacs of the human record yield long series of data that, when combined, assemble a global account of daily weather. With a few short-lived exceptions, regional or national meteorological networks have only existed since the mid-1850s. Prior to this time, weather records were primarily kept by citizen scientists, working alone or in small groups, noting everything from observations of sky conditions to comprehensive instrumental readings. One of these dedicated citizen scientists was Thomas Jefferson who on 1 July 1776 began a record of the weather that continued intermittently through 28 June 1826.

These 19,000 temperature readings and observations of sky conditions, periodic runs of pressure, humidity, wind direction and force, precipitation measurements, and phenological observations, or notes on the seasonal changes seen in wildlife and plant growth, comprise a valuable resource for reconstructing the climate of the early American Republic. However, the 140 pages of data have not been particularly accessible to researchers. These records, written in notebooks, on blank pages of financial memoranda, and on loose sheets of paper, are held by five different repositories and by private individuals. The tables Jefferson constructed vary in format, keys to abbreviations, asterisks, and other symbols are not included on most pages, repeated terms or numbers are often implied, and obsolete or provincial names are occasionally used for bird and plant notes. These inconsistencies add another layer of difficulty to the lack of accessibility. The Jefferson and Climate Weather Records, an open access digital resource, brings these observations together in a standardized format designed to overcome these barriers. Data is presented in its original format, as high resolution scans of Jefferson’s pages, and is transcribed into a uniform table, easily searched or downloaded for further manipulation. Data visualizations, annotation, and related documents provide context for the observations collected from nearly 100 locations, most comprehensively Washington, D.C., Paris, and Charlottesville, Virginia.

The transcription of a portion of Jefferson’s record from March 1796

The transcription of a portion of Jefferson’s record from March 1796 (The Jefferson Weather & Climate Records).

Jefferson encouraged scientific inquiry among his network of acquaintances with a similar “fondness for philosophical studies.” In a 1778 letter to friend Giovanni Fabbroni in Florence, Italy, Jefferson wrote, “It might not be unacceptable to you to be informed for instance of the true power of our climate as discoverable from the Thermometer, from the force and direction of the winds, the quantity of rain, the plants which grow without shelter in the winter &c. On the other hand we should be much pleased with cotemporary observations on the same particulars in your country, which will give us a comparative view of the two climates.” Explorers William Dunbar and Meriwether Lewis and William Clark were instructed to take notes on the climate, “as characterized by the thermometer” of the country they explored, and Jefferson encouraged friends like James Madison to keep their own weather record. These citizen scientists and others less famous who also kept individual weather diaries have left a valuable resource for understanding human history, improving prognostication, tracking plant and animal responses to changes in the environment, and for creating models of future weather.

Integrating the Jefferson weather records with those of other observers to create a more comprehensive data series will maximize their contribution to the reconstruction of climate history. To that end, the North American Climate History project (NACH), a collaboration of the Center for Digital Scholarship at the American Philosophical Society (APS) in Philadelphia, the Center for Digital Editing at the University of Virginia, and the Jefferson Weather Records, was established to “rescue” weather records written in diaries, scrawled in notebooks, or noted on the blank pages of almanacs and stored in libraries, archives, and historical societies. Weather records of Dunbar, Lewis and Clark, and Madison are held at the APS where they and other weather journals are being transcribed and made available digitally. Combining these records with Jefferson’s and adding data sets from other manuscripts will create a resource that provides unfettered access to manuscript records that would otherwise remain unsearchable. One of only two such projects in North America, NACH will be an open access repository of transcribed, digitized, contextualized, and searchable data. It will join the International Atmospheric Reconstructions over the Earth (ACRE) project, Data Rescue Archives and Weather (DRAW) of Canada, the Japan-Asia Climate Data Program, the University of East Anglia Climatic Research Unit, Euro-Climhist, Climate Australia, and other data rescue projects. The work of all these projects is essential for understanding past weather and its concomitant effects on the human and natural worlds, increasing knowledge of weather patterns and catastrophic events to improve forecasting and streamline emergency planning, and preparing for, or mitigating, consequences for the environment.

Welcome to our Revolving Desk

Here in our version of a swiveling cupboard, we will offer an occasional series of brief essays by a rotating slate of authors from our project. Our goal is to provide vignettes to illuminate subjects we encounter in our work. This is our opportunity to say a little more about bits that have caught our interest and, we hope, will catch yours.

|August 2023

A Place to Lay Their Heads: Housing in Early Washington City

When the seat of government officially moved to the banks of the Potomac in late 1800, those who traveled with it found little trade, few roads to regulate, and empty lots. When members of the second session of the Sixth Congress began filtering into Washington, it immediately became clear that finding a place to lay their heads would not be easy in this village capital.

|March 2024

Postal Dreams Deferred

In 1806, Jefferson received an atypical request for pardon. The case draws interest for a recently passed law that the defendants had unknowingly violated: they had employed Black mail carriers on the postal route they managed, which connected New York and Philadelphia.

|January 2024