A forecast region is a unique geographical area for which individual weather reports are issued.
In Canada, the Meteorological Service divides the country into several forecast regions for the purpose of issuing routine text forecasts and weather warnings, as Canada's provinces and territories do not use a common second-level administrative division scheme similar to the division of states into counties and parishes in the United States.
Outside of Nunavut and the Northwest Territories, CLCs are assigned using the format 0paabb, where 0 is a constant, p is a province or provincial or territorial grouping, aa refers to a specific forecast region, and bb, if nonzero, refers to a sub-region.
In Nunavut and the Northwest Territories, where population densities are much lower than elsewhere in the country, the format is 09aaa0, where aaa refers to the forecast region.
CLCs are also assigned to the areas of international waters for which Canada issues maritime navigation and weather warnings.