A new analysis of the maximum and minimum temperature trends is presented featuring the recently-created Canadian Historical Temperature Database (CHTD). The database contains monthly mean maximum and minimum temperature datasets for 210 Canadian stations. Missing monthly values have been estimated using highly correlated neighbours, and relative homogeneity was assessed using a Canadian developed technique based on regression models. Adjustments were performed for identified inhomogeneities corresponding to station relocation, changes in instrumentation and changes in observing practices.
Monthly departures series from the 1961-1990 reference period were obtained at individual station. They were used to generate gridded datasets of monthly temperature departures using the Gandin Optimal Interpolation technique. The grid covers the nation at 50 km resolution. Linear trends were calculated at each grid point for maximum and minimum temperature departures separately. Since prior to the early 1940s there are few data available in the northern part of the country, the trends were produced for two periods of time: 1895-1995, for the area south of 60N, and 1946-1995 for the nation as a whole. Seasonal and annual trends are mapped and time series are graphed for the analysis of spatial and temporal temperature variation in Canada.