The normal high temperature for a given day determined by the temperature of a place averaged over a period of time, often 30 years. This is also described as climate information. Climate information includes the statistical weather information that tells us about the normal weather, and also the range of weather extremes for a location. Most weather forecasters rely of past weather to predict the normal high temperature of a given day.
The average high or low temperature is the normalized high or low temperature for at least a 30 year period. Therefore, an average high is a statistical average. Records need to be kept at least 30 years for an average high temperature, for the information to be statistically meaningful.
