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.
Peek at the underside of the steak every 60 seconds or so until a nice row of grill marks appears. Note how long it took to get those grill marks on the timer/stopwatch. It should take three to six minutes depending on the heat of the grill. Rotate (not flip) the steak 45 degrees and allow the steak to sear for as long as it took to get the first set of grill marks. Now is the time to flip and repeat the process on the other side. Once the steak has cross-hatch grill marks on both sides, send it to the side with no heat.