Climate Trends and Variations Bulletin

Temperature & Precipitation in Historical Perspective

Spring 2002 

National Temperature

The Canadian climate certainly can be interesting.  After 19 consecutive seasons of above normal temperatures, Canada finally experienced a cooler than normal spring (March, April, and May).  In fact, Canada, as a whole, had its 5th coolest spring, since comparable nationwide records began in 1948, at 1.4°C below normal, based on preliminary data.  The map to the right shows that most of Canada had temperatures more than 1°C below normal, with parts of northern Saskatchewan and Alberta experiencing temperature as cold as 5°C below normal.  Vancouver Island, southern Ontario, southern Quebec, the Maritimes, and most of the Arctic islands had temperatures near normal this spring.  Only northern Yukon and Northwest Territories experienced warmer than normal temperatures this spring.

The chart to the left shows what a difference a year makes.  The previous four springs were among the warmest on record, and this spring was among the coolest. However, springs historically, have continued to get warmer, with a warming of 1.4°C over the 55-year period, as shown by the dashed red line in the chart.  The national warmest/coolest temperature table lists the ten coolest and warmest springs for the entire country.  The coolest spring continues to be 1974 (-1.8°C), and the warmest was 1998 (+3.2°C). The national temperature departures table shows the full list of years in the order from warmest to coolest one.

National Precipitation

As a whole, Canada had a wetter than normal spring.  Spring 2002 was the 18th wettest out of the 54-year period of record, 5.6% above normal, based on preliminary data. But, this summary number doesn't convey the complex precipitation picture this spring.  The map to the right shows that western and northern B.C., Yukon, western Nunavut, and most of Alberta and Saskatchewan experienced drier than normal conditions this spring.  Central B.C., eastern Northwest Territories, Baffin and Ellesmere Islands, most of Manitoba, southern Ontario, southern Quebec, northern Quebec and  parts of the Maritimes all had wetter than normal conditions this spring.  The wettest spring was 1979 (+28.8%) , and the driest spring was in 1956 (-21.3%), as shown in the national precipitation wettest/driest table.  The national precipitation departures table shows the full list of years in the order from wettest to driest.

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 wetter than normal spring, nationally, is in keeping with most of the springs since the 1970's.  Only five of the last 31 springs have been below normal, as shown in the chart to the left.  In contrast, the previous three seasons were drier than normal, as shown in the consecutive seasons graph.  The wetter than normal conditions around the Great Lakes has helped to raise lake levels back to near normal.

Continue to the Regional Analysis...

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