April Mean Daily Minimum and Maximum Temperatures

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Abstract

Minimum temperatures in April are below freezing for most of Canada. Below-freezing maximum temperatures in April are restricted to northern Canada and the extreme northern portions of Ontario and Quebec adjacent to Hudson Bay. The map shows the mean daily minimum and maximum temperatures for April.

Minimum temperatures in April are below freezing for most of Canada. Only extreme southern Ontario, extreme southern Nova Scotia and coastal British Columbia have normal minimum temperatures above freezing. This represents a major warming from January values for all of southern Canada, but winter conditions still dominate the north.

Below-freezing maximum temperatures in April are restricted to northern Canada and the extreme northern portions of Ontario and Quebec adjacent to Hudson Bay. Lengthening days and strengthening sunshine bring about a moderation in temperature in all parts of the country. In the high Arctic, maximum temperatures range from -15 to -30ºC, so winter is very much present despite the arrival of spring weather across southern Canada.

Data Source and Methodology

The 1971 to 2000 temperature climate normals were calculated by Environment Canada in a manner consistent with the methodology of the World Meteorological Organization. For temperature, a monthly maximum (minimum) average was computed from the daily maximum (minimum) temperature observations. The normal is a simple arithmetic average of the monthly minimum or maximum temperatures for the specified period. These spatial models have been developed using the thin plate smoothing spline algorithms of ANUSPLIN, which is a mathematically sophisticated approach to generating climate maps at varying spatial and temporal scales. The Canadian Forest Service has been working in partnership with several staff in Environment Canada’s Meteorological Service of Canada, the Australian National University (the creator of ANUSPLIN) and others to develop a variety of climate models that cover both Canada and North America.