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.
A lot of skirt steak recipes call for marinating the meat before grilling it, and because of its looser structure, skirt steak will absorb the flavors of the marinade quite well. But there's no need to marinate it for more than 30 minutes or so, as marinating does not tenderize meat.