Spatial Variability of Summer Droughts and Heatwaves in Southern Canada

Drought is a short- to long-term risk that challenges access to water. Prolonged droughts could inflict agricultural and economic losses and cause social hardships. Southern Canada is home to the majority of the country's population and serves as the country's primary economic hub. This region has more climatic diversity than the northern part and is prone to drought during the summer months. This study investigates the relationship between the occurrence of daily summer droughts and heat waves in southern Canada. In this regard, from 1985 to 2017, homogenized daily precipitation and maximum temperature data from 26 selected stations were used from May to September. Daily droughts have been calculated using the effective drought index (EDI). The threshold temperature for calculating heat waves was 32 ºC. We compared the results from southern Canada to those from the Prairie region. According to the findings, all types of daily droughts occur in southern Canada, but severe and extreme droughts are more common in the southern Prairies. Long-term daily droughts with the highest and lowest mean values were observed at the Toronto and St Jerome stations, respectively. Manitoba had the greatest variability in drought intensity between stations, with 1.96, and Quebec had the least, with 0.76. The increasing trend of daily droughts in Manitoba has been greater than in other southern Canadian provinces. The longest heatwaves occurred in Saskatchewan stations, with daily droughts intensifying in the long run.