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.
Better to grill on direct heat. Depending on thickness of steak and temp of grill, do each of the following for 2.5 to 3.5 minutes. 1)Place steak on very hot oiled grill. 2) After 2.5-3.5 minutes, rotate steak 90 degrees to get crossed grill marks. 3) After 2.5-3.5 minutes, flip the steak and repeat steps 1&2 to get crossed grill marks on other side.