A weather forecast-based fluid heating control system having at least one hot fluid delivery point, the control system including a controller adapted to control a fluid supply to a setpoint temperature, a means for obtaining the forecasted air temperature at a future time of the location of the control system and a means for obtaining the current air temperature at a current time of the location of the control system. The setpoint temperature of the fluid supply is adjusted by an adjustment amount if the difference between the forecasted air temperature of the location of the control system and the current temperature at the current time of the location of the control system exceeds a pre-determined threshold.