The National Demand Forecast Day data is part of the 2-14 day forecast produced each working day by the System Operator as required by section 4.1.2 in Operating Code 2 of the Grid Code.

It is produced using the same methodology as the daily National Demand Forecast. The figure published for each day in the 2-14 day forecast is a half hourly average MW value for the peak half hour in the day.