Daily minimum and maximum temperature in the St-Lawrence Valley, Quebec: two centuries of climatic observations from Canada

Abstract

Climatological and meteorological observations in Canada begin in the first half of the 18th century. Continuous daily observations of the weather and climate for the province of Quebec start in the late 18th century. Estimates of daily minimum and maximum temperatures from historical fixed hour observations are provided from regression models based on hourly data from the modern period. Observations of temperature from different locations and observers are compared and regressions models are used to compile a single series of daily minimum and maximum temperatures extending back to 1742, with nearly continuous observations from 1798. Mean, absolute minimum and maximum values suggest considerable variability in the climate over the past two centuries. Based on a variety of climate indicators, exceptionally warm years include 1808, 1848, 1870, 1953 and 1998, while cold years include 1809, 1816, 1818, 1875 and 1904. Analysis of frost days and growing season length suggest a reduction in cold temperatures over past 200 years, while the incidence of cold spells and heat waves has decreased.