Early Instrumental Temperature Observations in Spain (1790s)

This dataset compiles early instrumental temperature records from four locations in Spain—Ferrol, Barcelona, Madrid, and Cádiz—spanning the last decade of the 18th century. It provides rare historical insights into regional climate variability prior to the onset of modern meteorological networks. All temperatures are reported in degrees Celsius, and only existing (non-interpolated) values are included.

A) Ferrol

Midday temperature measurements (approximately 12:00 p.m.) were recovered from four distinct manuscript sources housed in the Archivo Histórico del Real Instituto y Observatorio de la Armada (AHROA). All observations were made at the Royal Institute and Observatory of the Spanish Navy in Ferrol.

• Source #1: November 6, 1792 – July 4, 1793

• Source #2: November 17, 1792 – December 31, 1793

• Source #3: July 6, 1792 – July 1, 1793

• Source #4: January 1, 1794 – December 31, 1795

Only original observed values are included.

B) Barcelona

Temperature readings at approximately 2:00 p.m. were compiled from two distinct sources:

• 1791–1793: Data obtained from manuscript records at the Reial Acadèmia de Medicina de Catalunya (RAMC) upon request.

• 1794–1799: Extracted from the Diario de Barcelona, publicly available via the Arxiu de Revistes Catalanes Antigues (ARCA): https://arca.bnc.cat

Data coverage is limited to the period from May 1 to June 15 of each year. Only recorded temperature values are included.

C) Madrid

Midday temperatures (around 12:00 p.m.) were retrieved from issues of the Diario de Madrid, available through the Hemeroteca Digital of the Spanish National Library: https://hemerotecadigital.bne.es

Data coverage is limited to May 1 to June 15 over the period 1790-1799. Only original temperature values are included.

D) Cádiz

Daily maximum temperatures were extracted from a manuscript (signature AH1076) preserved at the Archive and Library of the Royal Institute and Observatory of the Spanish Navy (AHROA). The manuscript was photographed and digitized by the authors for data retrieval.

Data coverage is limited to May 1 to June 15 over the period 1789-1795. Only original recorded values are included.