Extreme Heat Warning

* WHAT...For the Dense Fog Advisory, visibility as low as a quarter mile at times in dense fog. For the Extreme Heat Warning, a dangerous combination of oppressively hot and humid conditions with heat index values between 105 to 115 expected.

* WHERE...In Illinois, Bureau, Putnam, Carroll, Henry IL, Jo Daviess, Stephenson, and Whiteside Counties. In Iowa, Clinton, Jackson, and Dubuque Counties.

* WHEN...For the Dense Fog Advisory, until 8 AM CDT this morning. For the Extreme Heat Warning, until 10 PM CDT this evening.

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