* WHAT. Heat index values up to 105 degrees Tuesday afternoon and near 100 degrees Wednesday afternoon. * WHERE. Adams, Cumberland, Dauphin, Franklin, Lancaster, Lebanon, Perry, and York Counties. * WHEN. For the Excessive Heat Warning, until 8 PM EDT Tuesday. For the Heat Advisory, from 8 PM Tuesday to 8 PM EDT Wednesday. * IMPACTS. Heat related illnesses increase significantly during extreme heat and high humidity events.

* WHAT. Heat index values up to 110 expected. * WHERE. Portions of central and north central Maryland and central, northern and northwest Virginia. * WHEN. From 11 AM to 8 PM EDT Tuesday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur. * ADDITIONAL DETAILS. Very warm and humid conditions will persist into the overnight hours, adding heat stress to those without air conditioning. Ensure to stay hydrated and find ways to stay cool.

* WHAT. Dangerously hot conditions with heat index values up to 111 expected. * WHERE. Portions of central, northeast, northern and southern Maryland, The District of Columbia and central and northern Virginia. * WHEN. From 11 AM to 8 PM EDT Tuesday. * 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, adding heat stress to those without air conditioning. Ensure to stay hydrated and find ways to stay cool.

* WHAT. Dangerously hot conditions with heat index values up to 109 expected. * WHERE. In Maryland, Washington County. In Virginia, Shenandoah, Frederick VA, Page, Warren and Clarke Counties. In West Virginia, Morgan, Berkeley and Jefferson Counties. * WHEN. From 11 AM to 8 PM EDT Tuesday. * 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, adding heat stress to those without air conditioning. Ensure to stay hydrated and find ways to stay cool.

* WHAT. South winds around 10 kt with gusts up to 20 kt expected. * WHERE. Tidal Potomac River from Key Bridge to Cobb Island MD, Patapsco River including Baltimore Harbor, and Patuxent River to Broomes Island MD. * WHEN. From 2 PM this afternoon to 8 PM EDT this evening. * IMPACTS. Conditions will be hazardous to small craft.

* WHAT. South winds 10 to 15 kt with gusts up to 20 kt expected. * 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. From 2 PM this afternoon to 2 AM EDT Wednesday. * IMPACTS. Conditions will be hazardous to small craft.

* WHAT. Dangerously hot conditions with heat index values up to 107 expected. * WHERE. In Maryland, Washington County. In Virginia, Shenandoah, Frederick, Page, Warren and Clarke Counties. In West Virginia, Morgan, Berkeley and Jefferson Counties. * WHEN. From 11 AM this morning to 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. * ADDITIONAL DETAILS. Very warm and humid conditions will persist into the overnight hours, adding heat stress to those without air conditioning. Ensure to stay hydrated and find ways to stay cool.

* WHAT. Dangerously hot conditions with heat index values up to 110 expected. * WHERE. Portions of central, northern and southern Maryland, The District of Columbia, and central and northern Virginia. * WHEN. From 11 AM this morning to 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. * ADDITIONAL DETAILS. Very warm and humid conditions will persist into the overnight hours, adding heat stress to those without air conditioning. Ensure to stay hydrated and find ways to stay cool.

* WHAT. Heat index values up to 108 expected. * WHERE. Portions of central and north central Maryland and central, northern and northwest Virginia. * WHEN. From 11 AM this morning to 8 PM EDT this evening. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur. * ADDITIONAL DETAILS. Very warm and humid conditions will persist into the overnight hours, adding heat stress to those without air conditioning. Ensure to stay hydrated and find ways to stay cool.

* WHAT. Heat index values up to 110 degrees this afternoon and near 100 degrees Wednesday afternoon. * WHERE. Adams, Cumberland, Dauphin, Franklin, Lancaster, Lebanon, Perry, and York Counties. * WHEN. For the Excessive Heat Warning, until 8 PM EDT this evening. For the Heat Advisory, from 8 PM this evening to 8 PM EDT Wednesday. * IMPACTS. Heat related illnesses increase significantly during extreme heat and high humidity events.