This web site provides adjusted and homogenized climate data for many climatological stations in Canada. These data were created for use in climate research including climate change studies. They incorporate a number of adjustments applied to the original station data to address shifts due to changes in instruments and in observing procedures. Sometimes the observations from several stations were joined to generate a long time series. The adjusted and homogenized data are provided for four climate elements: surface air temperature, precipitation, surface pressure, and surface wind speed.