Climate Trends and Variations Bulletin

Temperature & Precipitation in Historical Perspective

Summer 2007

National Temperature

The summer of 2007 was the 7th warmest Canada has experienced since nationwide records began in 1948, 0.9°C above normal, based on preliminary data. The warmest summer was 1998, 1.8°C above normal, and the coolest year was 1968, 0.8°C below normal. The map to the right shows that most of the country experienced temperatures less than 1°C above normal, with some of the arctic islands having temperatures slightly more than 2°C above normal. With the exception of the springs of 2002 and 2004, seasonal temperatures have remained above or near normal for the last 10 years, as shown in the consecutive seasons graph.

The graph to the left shows that summer temperatures have generally been increasing nationally, with temperatures remaining at or above normal since 1993. The red dashed line represents a warming trend of 0.9°C over the last 60 years. Listed in the national warmest/coolest temperature table are the ten coolest and warmest summers for the entire country. The national temperature departures table shows the full list of summers in the order from warmest to coolest, and shows that 5 of the warmest 10 summers have occurred within the last 10 years.

National Precipitation

Overall, Canada experienced its 28th wettest summer, out of the 60-years of record, 2.9% above normal, based on preliminary data.  The map to the right shows the wetter than normal areas, those more than 40% wetter than normal, include: northern B.C.; southern Yukon; the border area between Northwest and Nunavut territories; and Nova Scotia. Areas of southern B.C., Alberta, and Saskatchewan, areas in central and southern Ontario, and an area covering some of the arctic islands all experienced at least 40% less precipitation this summer.

It should be noted that "normal" precipitation in northern Canada is generally much less than it is in southern Canada, and hence a percent departure in the north represents much less difference in actual precipitation than the same percentage in the south. The national precipitation rankings are therefore often skewed by the northern departures and do not represent rankings for the volume of water falling on the country.

The graph to the left shows that most summers since 1973 have had precipitation levels near or above normal. As shown in the national precipitation wettest/driest table, the wettest summer was 2005 (+21.2%) and the driest was 1958 (-14.3%).  The national precipitation departures table shows the full list of summer precipitation values in order from wettest to driest.  The consecutive seasons graph shown that when comparing the seasonal values over that last three years, precipitation values have tended to be wetter than normal.

Continue to the Regional Analysis...

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