Self-initialized packers for use in high temperature steam injection applications in wellbores are provided. The packers include an actuating mechanism for setting a packing element for sealing within an openhole or cased hole. The actuating mechanism includes an actuator sleeve that includes an actuating element constructed from a shape memory alloy that has a transformation temperature range greater than a geothermal temperature of the wellbore, and is actuated upon heating from steam injection. Systems and methods of using the packers are also provided.