The impact of climatic variability on the environment is of great importance to the agricultural sector in Canada. Monitoring the impacts on water supplies, soil degradation and agricultural production is essential to the preparedness of the region in dealing with possible drought and other agroclimate risks. Derived normal climate data represent 30-year averages (1961-1990, 1971-2000, 1981-2010, 1991-2020) of climate conditions observed at a particular location. The derived normal climate data represents 30-year averages or “normals” for precipitation, temperature, growing degree days, crop heat units, frost, and dry spells. These normal trends are key to understanding agroclimate risks in Canada. These normal can be used as a baseline to compare against current conditions, and are particularly useful for monitoring drought risk.

Contained within the 5th Edition (1978 to 1995) of the National Atlas of Canada has a large that shows the extent of permafrost and abundance of ground ice; mapping units are based on physiographic regions. Point data on map give permafrost temperature and thickness for specific sites. The second, smaller, map shows the mean annual ground temperatures. Graphs show four shallow temperature profiles (to 25 metres depth), and four deep temperature profiles (to several hundred metres depth).

Monthly 30-year Average Mean Temperature represents the average monthly mean temperature calculated at a given location averaged across a 30 year period (1961-1991, 1971-2000, 1981-2010, 1991-2020). These values are calculated across Canada in 10x10 km cells.

Monthly 30-year Average Minimum Temperature represents the average monthly minimum temperature calculated at a given location averaged across a 30 year period (1961-1991, 1971-2000, 1981-2010, 1991-2020). These values are calculated across Canada in 10x10 km cells.

Monthly 30-year Average Maximum Temperature represents the average monthly maximum temperature calculated for a given location averaged across a 30 year period (1961-1991, 1971-2000, 1981-2010, 1991-2020). These values are calculated across Canada in 10x10 km cells.

Crop/Corn Heat Units (CHU) is a temperature-based index often used by farmers and agricultural researchers to estimate whether the climate is warm enough to grow corn. Daily crop heat units are calculated from minimum and maximum temperatures with separate calculations for day and night. The daytime relationship sets the minimum at 10 C for growth up to a maximum of 30 C, beyond which growth slows. These values are calculated across Canada in 10x10 km cells.

Growing Season Frost Free Period (0 °C) is defined as the count of the number of days from the day after the last spring frost (0 °C) to the day before the first fall frost (0 °C). These values are calculated across Canada in 10x10 km cells.

Growing Degree Days (GDDs) are used to estimate the growth and development of plants and insects during the growing season. Insect and plant development are very dependent on temperature and the daily accumulation of heat. The amount of heat required to move a plant or pest to the next development stage remains constant from year to year. However, the actual amount of time (days) can vary considerably from year to year because of weather conditions. Base temperatures are a point below which development does not occur for the organism in question. Base 15 temperatures are commonly used for general insect development. These values are calculated across Canada in 10x10 km cells.

Frost Day Count (0 °C) is defined as the number of days in a calendar month where the minimum daily temperature for the climate day was at or below 0 °C. These values are calculated across Canada in 10x10 km cells.

Growing Degree Days (GDDs) are used to estimate the growth and development of plants and insects during the growing season. Insect and plant development are very dependent on temperature and the daily accumulation of heat. The amount of heat required to move a plant or pest to the next development stage remains constant from year to year. However, the actual amount of time (days) can vary considerably from year to year because of weather conditions. Base temperatures are a point below which development does not occur for the organism in question. Base 5 temperatures are commonly used for alfalfa, canola and general plant growth. These values are calculated across Canada in 10x10 km cells.