This article will address the issue of Climatological normal, which is of great relevance in the current context. From different perspectives, the importance and impact of Climatological normal in contemporary society will be analyzed. Likewise, various aspects related to Climatological normal will be examined, in order to provide a comprehensive view on this topic. Through a multidisciplinary approach, the implications of Climatological normal will be explored in different areas, from the personal to the global level. Thus, this article aims to offer a complete and updated vision of Climatological normal, with the purpose of generating an enriching debate and encouraging critical reflection on this topic.
Climatological normal or climate normal (CN) is a 30-year average of a weather variable for a given time of year. Most commonly, a CN refers to a particular month of year, but it may also refer to a broader scale, such as a specific meteorological season. More recently, CN have been reported for narrower scales, such as day of year and even hourly scale.
Climatological normals are used as an average or baseline to evaluate climate events and provide context for year-to-year variability. Normals can be calculated for a variety of weather variables including temperature and precipitation and rely on data from weather stations. Variability from the 30-year averages is typical and climate variability looks at the magnitude of extremes. Climatological standard normals are overlapping periods updated every decade: 1971–2000, 1981–2010, 1991–2020, etc.
The term "normal" first appeared in the literature by Heinrich Wilhelm Dove in 1840 and the concept was formalized by the International Meteorological Committee in 1872. The use of the 30-year period of normals began in 1935 with the 1901-30 period. The continued use of 30 year normals has increasingly been called into question due to substantial evidence that the stationarity of climate statistics can no longer be taken for granted due to climate change. This has led to alternative definitions such as "Optimal Climate Normal" and the "Hinge Fit" approach to supplement the standard 30 year normals which are still commonly used.