Årsnormalen
Årsnormalen is a climatological concept used in meteorology to describe the long-term, typical weather for a location. It represents the average value of a weather variable over a reference period of 30 consecutive years. By averaging daily or monthly observations across this 30-year window, a normal value is established for each day or month, such as the normal temperature for January 15 or the normal precipitation for March.
Purpose and use are to provide a stable baseline against which current weather can be compared. The
Reference periods are periodically updated to reflect climate change and changing conditions. The World Meteorological Organization
Calculation typically involves the arithmetic mean of the 30-year data for each specific day, month, or variable.
Limitations include that normals are not predictions; they describe past conditions and may gradually shift as
Årsnormalen is used in weather forecasting, climate reporting, agriculture, infrastructure planning, and media communication to describe