However, itâs also a time to be aware of the dangers soaring temperatures can bring. Extreme heat is the number one weather-related killer in the U.S, claiming more than 650 lives across the nation each year, according to the Centers for Disease Control and Prevention.
1 In a bowl whisk together garlic, extra virgin olive oil, balsamic, 1/4 cup red wine, 1 tablespoon chopped rosemary, salt and pepper.  Place flat iron steak in a resealable plastic bag. Pour marinade over the top. Shake to coat steak in marinade. Refrigerate for 8 hours or overnight.
7Repeat the process on this side of the steak, cook for 3 - 4 minutes, rotate, cook for another 2 - 3 minutes. 8Remove from the grill and place on a platter, but let it sit for about 5 minutes before you cut into the flat iron steak to let the juices re-distribute. 9Most flat iron steaks have a line of gristle running right down the middle.