A beef roast cooked to medium-rare should have an internal temperature of 145°F - 150ºF after the resting period, and a roast cooked to medium should have an internal temperature of 150°F to 160ºF. (See the note below). See Beef Doneness for more information on proper cooking temperatures.o not cover the roast and do not add any liquid (liquid is used for braising, not roasting). Allow the beef to roast at 450°F for 45 minutes and then begin checking the internal temperature of the meat with a meat thermometer.