THE PILOT WAS LANDING A WHEEL EQUIPPED AIRPLANE AT A REMOTE AIRPORT AS PART OF A SCHEDULED CHARTER FLIGHT WITH TWO PASSENGERS. THE PILOT HAD LANDED AT THE AIRPORT EARLIER IN THE DAY AND WAS AWARE THAT THE RUNWAY SURFACE WAS COVERED WITH SNOW AND ICE. WHEN THE AIRPLANE TOUCHED DOWN, THE AIRPLANE WEATHERVANED TO THE LEFT INTO AN 18 KNOT CROSSWIND. THE PILOT'S INPUT OF RUDDER AND NOSE WHEEL STEERING HAD NO EFFECT. THE AIRPLANE SLID OFF THE DEPARTURE END OF THE RUNWAY AND DOWN AN EMBANKMENT INTO A SNOW BANK.