A heating, ventilation, or air conditioning (HVAC) system for a building includes, a chiller, a heat exchanger separate from the chiller, and a controller. The chiller is configured to provide mechanical cooling for a cooling load in the building when the HVAC system operates in a mechanical cooling state. The heat exchanger is configured to provide free cooling for the cooling load in the building when the HVAC system operates in a free cooling state. The controller is configured to predict outside air temperature and transition the HVAC system from operating in the mechanical cooling state to operating in the free cooling state in response to a determination that the predicted outside air temperature will be less than the free cooling temperature threshold for at least the minimum free cooling time.