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.