Extreme heat has arrived in Southern Nevada. An excessive heat warning is in effect for the valley through Thursday night. A high pressure system over the Southwest will cause temperatures to rise as much as ten degrees above normal. The high in Las Vegas will exceed 110, with even higher temperatures at Lake Mead, Laughlin, and Mesquite. Death Valley could see a high of 122 degrees. Local residents are urged to drink plenty of fluids and limit outdoor activity during the daytime hours. And another reason not to go outside...an air quality advisory remains in effect for Clark County through Saturday, due to smoke from wildfires in California and Arizona, along with Fourth of July barbecues and fireworks.