Contained within the 3rd Edition (1957) of the Atlas of Canada is a plate that shows six maps of the Canadian ranges in temperature. The map entitled Mean Annual Maximum Temperature shows the mean of the highest temperature recorded each year from 1921 to 1950 inclusive. The Mean Annual Minimum Temperature map shows the mean of the lowest temperature recorded each year during the 30 year period. The two temperature extreme maps show the highest and lowest temperatures officially recorded during the same period. Two small maps show the number of days on which temperatures of 90 degrees F (32.2 degrees C) or higher were recorded and the numbers of days on which the temperature was 0 degrees F (-17.8 degrees C) or lower.