* WHAT. South winds 10 to 20 kt with gusts up to 25 kt expected. * WHERE. Tidal Potomac River from Key Bridge to Cobb Island MD, Chesapeake Bay north of Pooles Island MD, and Patapsco River including Baltimore Harbor. * WHEN. From 10 AM to 6 PM EDT Today. * IMPACTS. Conditions will be hazardous to small craft.

* WHAT. For the Small Craft Advisory, south winds 10 to 20 kt with gusts up to 25 kt expected. * WHERE. Chesapeake Bay from Pooles Island MD to Drum Point MD, Tidal Potomac from Cobb Island MD to Smith Point VA, Chester River to Queenstown MD, Eastern Bay, Choptank River to Cambridge MD and the Little Choptank River, and Patuxent River to Broomes Island MD. * WHEN. Until 6 PM EDT this evening. * IMPACTS. Conditions will be hazardous to small craft.

* WHAT. Dangerously hot conditions with heat index values up to 110 expected. * WHERE. Portions of central and southern Maryland, The District of Columbia, and portions of the northern neck of Virginia. * WHEN. From noon today to 8 PM EDT. * IMPACTS. Extreme heat and humidity will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities. * ADDITIONAL DETAILS. Very warm and humid conditions will persist into the overnight hours. Ensure to stay hydrated and find ways to stay cool.

* WHAT. Heat index values up to 108 expected. * WHERE. Portions of central and northern Maryland, portions of northern and central Virginia. * WHEN. From noon today to 8 PM EDT. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur.

* WHAT. Heat index values up to 105 expected. * WHERE. Portions of north central and western Maryland, northwest and western Virginia and eastern West Virginia. * WHEN. From noon today to 8 PM EDT. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur.

* WHAT. Dangerously hot conditions with heat index values up to 112 expected. * WHERE. Portions of central, northern and southern Maryland, The District of Columbia and central and northern Virginia. * WHEN. Until 8 PM EDT this evening. * IMPACTS. Extreme heat and humidity will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities.

* WHAT. Heat index values up to 109 expected. * WHERE. Portions of central, north central, northeast and northern Maryland and central, northern and northwest Virginia. * WHEN. Until 8 PM EDT this evening. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur.

* WHAT. Heat index values up to 105. * WHERE. Portions of north central and western Maryland, northwest and western Virginia and eastern and panhandle West Virginia. * WHEN. Until 8 PM EDT this evening. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur.

* WHAT. South winds 10 to 15 kt with gusts up to 25 kt. * WHERE. Tidal Potomac River from Key Bridge to Cobb Island MD, Patapsco River including Baltimore Harbor, and Patuxent River to Broomes Island MD. * WHEN. Until 2 AM EDT Thursday. * IMPACTS. Conditions will be hazardous to small craft.

* WHAT. South winds 10 to 20 kt with gusts up to 30 kt. * WHERE. Chesapeake Bay north of Drum Point MD, Tidal Potomac from Cobb Island MD to Smith Point VA, Chester River to Queenstown MD, Eastern Bay, and Choptank River to Cambridge MD and the Little Choptank River. * WHEN. Until 4 AM EDT Thursday. * IMPACTS. Conditions will be hazardous to small craft.

* WHAT. Oppressive heat with afternoon heat indices between 100 and 105 degrees. * WHERE. Adams, Cumberland, Dauphin, Franklin, Lancaster, Lebanon, Perry, and York Counties. * WHEN. Until 8 PM EDT this evening. * IMPACTS. High temperatures and humidity may cause heat illnesses.