The Quantile Regression Ensemble Summer Year (QRESY) creation process starts by collecting hourly weather data over a long  period. Typically, weather files attempt to be representative of periods around 20-40 years, and here we do the same, however much longer periods could be used. The existence, variables and quality of hourly weather data varies depending on the location. The variables usually include temperature, atmospheric pressure, cloud cover, wind speed and wind direction, precipitation, etc.