The urban heat island effect and 'micro-climates' have a negligible impact on long term warming trends, especially when records are averaged over large areas. Also, rural temperature records show the same warming trends as urban ones. The 'evidence' on this site isn't relevant to arguments regarding the existing of global warming.
The site says nothing about global warming or the cause. The site does show that there is a consistent warming trend over summer months across all of Canada, and is most extreme in northern Canada. Also, I believe the Environment Canada data is accurate to within 0.2 degrees C.