A heat wave is impacting Siouxland. A heat advisory kicked off at noon and runs through tomorrow night for a large part of the region, including northwest Iowa and southeast South Dakota and Dixon and Dakota counties in northeast Nebraska. The heat index will reach into the triple digits. The National Weather Service says drink plenty of fluids, stay in air-conditioning if possible, stay out of the sun and take extra precautions if you work or spend time outside. State agricultural experts say