Climate Trends and Variations Bulletin

Temperature & Precipitation in Historical Perspective

Spring 2004

National Temperature

The spring of 2004 was cooler than normal for most of Canada. As a whole, Canada was 0.4°C cooler than normal, based on preliminary data, which ranks this as the 18th coolest spring since nationwide records began in 1948. The map to the right shows that temperatures were at least a degree below normal for parts of Quebec, Ontario, Manitoba, Saskatchewan, Albert and Yukon. Almost all of the Northwest Territories and Nunavut were below average with parts as cool as 4 degrees cooler than normal. British Columbia, most of Alberta and part of Southern Ontario were warmer than normal this spring. With temperatures cooler this spring, the run of seasons with above normal temperatures has ended. The consecutive seasons graph shows temperatures have been above normal for 26 of the last 28 seasons, with only this spring and the spring of 2002 below normal.

The graph to the left shows that below normal temperatures are the exception, and that generally temperatures have been above normal since 1975. The red dashed line represents a warming linear trend of 1.2°C over the last 57 years. Listed in the national warmest/coolest temperature table are the ten coolest and warmest springs for the entire country. This table shows that 1998 (+3.2°C) was the warmest spring, and 1974 (-1.8°C) was the coolest. The national temperature departures table shows the full list of years in the order from warmest to coolest, and shows that 4 of the warmest 10 springs have occurred within the last 10 years.

National Precipitation

Overall, Canada experienced a wetter than normal spring in 2004. It was the 11th wettest spring out of the 57-year period of record, 8.2% above normal, based on preliminary data.   The map to the right shows there were areas of above and below normal across the country. Most of Manitoba, Alberta, Ontario, Quebec, and Newfoundland and Labrador were wetter than normal. Areas of British Columbia, Alberta, Yukon, Northwest Territories, Nunavut, and the Maritimes experienced drier than normal conditions this spring.

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 this was the fourth spring in a row with national precipitation values above normal, and that conditions have generally been wetter since the early 1970s. As shown in the national precipitation wettest/driest table, the wettest spring was 1979 (+28.8%) and the driest spring was 1956 (-21.3%).  The national precipitation departures table shows the full list of springs in the order from wettest to driest, and shows that there have only been 6 springs in the last 30 years with springs drier than normal.  Over the last 4 years there are close to an equal number of seasons with drier and wetter than normal conditions, as shown in the consecutive seasons graph.

Continue to the Regional Analysis...

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