Environment Canada publish historical weather [0] as do the Met Office [1]. I also recently discovered that the BC government have their own air quality monitoring stations - and that data is also available [2].

[0] - https://climate.weather.gc.ca/index_e.html

[1] - https://www.metoffice.gov.uk/research/climate/maps-and-data/...

[2] - https://www2.gov.bc.ca/gov/content/environment/air-land-wate...