The development and updating of the Stockholm Historical Weather Observations data set is a collaboration between the Swedish Meteorological and Hydrological Institute and Stockholm University.
All individual temperatures observed at the old astronomical observatory have been digitized back to 1 January 1756. The data source for the period 1756-1861 is the hand-written diary of meteorogical observations made at the observatory, which is stored in the archive of the Royal Swedish Academy of Sciences for the period 1756-1858 and in the archive of the SMHI for the period 1859-1861. Data sources for the period 1862-1960 are the printed annual books, published by the SMHI or its predecessors, containing weather observations from all Swedish observing stations. These books, however, do not provide information about the observed daily temperature maxima and minima during 1870-1899, but the observed values are reported in the hand-written observation diary stored at the SMHI.
Digitizing of the individual observational data from 1756-1838 was made by staff at the SMHI in the mid-1990s. Digitizing of data from 1839-1960 was undertaken at Stockholm University in the late 1990s within the European Union FP4 project IMPROVE - Improved Understanding of Past Climatic Variability from Early Daily European Instrumental Sources. Data for 1961 onwards have been made available digitally by the SMHI.
The number of observations each day have changed through time:
The digitized temperature observations have been separated into several files.
Observational data from 1961 onwards belong to the SMHI, from which the original data can be obtained. Data used here for 2013 onwards were obtained by downloading from SMHI Öppna Data.