The Harrier's capacity to hover depends mostly on the total weight of the aircraft at the time.
Under some combat loads, it can't hover at all, but needs a runway to take off. When it lands, after expending munitions and fuel, it could easily weigh less than half of its take off weight.
The F-35 has capacity to replace the Harrier as well as the F-15 Strike Eagle. It is a very versatile aircraft that will do much to give the USA forward strike capabilty. Because of its very short runway needs, it can be operated by forward bases constructed by helicopter-borne crews using air-dropped equipment. It could also operate from mini-aircraft carriers without catapults.
David F Mayer