* WHAT. Heat index values up to 110 expected. * WHERE. Coastal Indian River, Coastal Martin, Coastal Saint Lucie, Coastal Volusia, Inland Indian River, Inland Martin, Inland Northern Brevard, Inland Saint Lucie, Inland Southern Brevard, Inland Volusia, Mainland Northern Brevard, Mainland Southern Brevard, Northern Brevard Barrier Islands, Northern Lake, Okeechobee, Orange, Osceola, Seminole, Southern Brevard Barrier Islands, and Southern Lake. * WHEN. From 11 AM this morning to 6 PM EDT this evening. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses.