An atmospheric water harvester includes a cooling member over which humid air flows to condense moisture from the atmosphere. The cooling member may be the evaporator of a conventional, gas vapor-based refrigeration circuit. If a gas vapor-based refrigeration circuit is used, the compressor of the circuit may be variable speed. A fan or impeller used to move air through the system may also be variable speed. Preferred embodiments are reconfigurable between at least two operational configurations such that to varying degrees the incoming air may be pre-cooled, before it passes over the cooling member, by heat exchange with colder air that has already flowed over the cooling member.