Bring to a boil then remove from heat and cool to room temperature or cooler.
To cool hot liquids quickly, place pot in sink full of ice cold water and stir liquid in pot and water outside of pot. The heat from the liquid transfers to the water. Drain water and repeat until the liquid has cooled.
Place turkey in a large stock pot and add ice water. Then add cooled brine.
Cover and refrigerate overnight. If the weather is very cold outside, you can even place covered pot outside or in a garage.