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On May 2016 an extreme large wildfire affected Fort McMurray of Canada, leading to the largest wildfire evacuation and the costliest natural disaster in Canadian history. This wildfire was caused by extremely warm and dry weather conditions in spring. Here we investigate thermodynamic and dynamic (atmospheric circulation) conditions, and teleconnections conducive to extreme wildfire climate of western Canada since 1871. Results show that the extreme wildfire was very likely an outcome of anthropogenic effects that increase the occurrence of a persistent upper ridge associated with a warm and dry weather over western Canada. Changes in dynamic conditions decreased temperature and increased precipitation, while changes in thermodynamic conditions increased temperature and decreased precipitation. Thus the observed increase in temperature and decrease in precipitation on 26 April-15 May over western Canada were caused by changes in thermodynamic conditions. Although the Pacific North American (PNA) pattern was teleconnected with the occurrence of certain synoptic circulation patterns over western Canada, changes in the occurrence of the synoptic circulation pattern associated with the extreme wildfire cannot be explained by increased occurrences of the positive phase of PNA. The El Nino-Southern Oscillation and the Pacific Decadal Oscillation have not been found to have contributed to wildfire weather in western Canada. The spring warming and drying trends since 1871 over western Canada cannot be attributed to changes in common teleconnections.