Heat Advisory

* WHAT...For the Dense Fog Advisory, visibility of a quarter to half mile in dense fog. For the Heat Advisory, heat index values up to 109 expected. For the Extreme Heat Warning, dangerously hot conditions with heat index values up to 113 expected. For the Extreme Heat Watch, dangerously hot conditions with heat index values up to 110 possible.

* WHERE...In Iowa, Fremont, Harrison, Mills, Montgomery, Page, Pottawattamie, and Shelby Counties. In Nebraska, Douglas and Sarpy Counties.

* WHEN...For the Dense Fog Advisory, until 10 AM CDT this morning. For the Heat Advisory, from noon today to noon CDT Sunday. For the Extreme Heat Warning, from noon to 9 PM CDT Sunday. For the Extreme Heat Watch, from Sunday evening through Monday evening.

* IMPACTS...Heat related illnesses increase significantly during extreme heat and high humidity events. Hot temperatures and high humidity may cause heat illnesses. Low visibility could make driving conditions hazardous.