The Mesonet long-term averages utilize 15 years of daily data (e.g. daily average, daily maximum/minimum, or daily total) for every current and past Oklahoma Mesonet station. For a station's data to be used in the graphs, at least 90% of the data must be valid during the respective period. Data from moved locations (e.g. "Norman - retired 2002" and "Norman") are not combined into a single station record. This method of calculating 15-year averages of weather data is also used by the U.S. Climate Prediction Center and has been found to be the best alternative to the World Meteorological Organization's 30-year averages (Wilks and Livezey 2013, Journal of Applied Meteorology and Climatology).
For more information on each of the variables, please view the Mesonet Long-Term Averages Variables