Climatological normal

Climatological normal or climate normal (CN) is a 30-year average of a weather variable for a given time of year.[1] 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.[2] More recently, CN have been reported for narrower scales, such as day of year and even hourly scale. [3]

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.[1] Climatological standard normals are overlapping periods updated every decade: 1971–2000, 1981–2010, 1991–2020, etc.