If you add boiling water to a cup at room temperature, what would you expect the final equilibrium temperature of the unit to be? You will need to include the surroundings as part of the system. Consider the zeroth law of thermodynamics.
According to the zeroth law of thermodynamics, when two objects with different temperatures are in thermal contact, the heat flows from hot object to the colder object till the temperature of both objects become same.
Since the temperature of surrounding is less than the temperature of the boiling water, the heat energy flows from hot water to the surrounding air so that they reaches thermal equilibrium with each other if place for long time.