Average date of the first autumn frost (Tmin ≤ 0, -1, -2, -3 or -4 °C) based on the period from 1979 to 2008.
This analysis was based on temperature values interpolated at 10 km using the ANUSPLIN method, based on data from the Ministère du Développement durable, de l'Environnement et des Parcs du Québec and from Environment Canada.
These values give a general indication of the frost risk for a region, but they are not necessarily representative of a specific site. Frost risk varies locally depending on a number of factors, particularly topography and proximity to a body of water.
The first autumn frost is associated with the first day on which the minimum daily temperature is less than or equal to lethal temperature. Like the last spring frost, this indicator is associated with various levels of probability linked to risks of crop growth ending or potential damage to crops.
It is important to consider the date of the last spring frost when choosing a crop or cultivar for a region.
