* WHAT. Heat index values up to 107 expected. * WHERE. Portions of central, northeast, northern and southern Maryland, The District of Columbia and central and northern Virginia. * WHEN. From noon to 8 PM EDT Thursday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur.

The areas affected include. Chesapeake Bay from North Beach to Drum Point MD. Chesapeake Bay from Pooles Island to Sandy Point MD. Chesapeake Bay from Sandy Point to North Beach MD. Chester River to Queenstown MD. Choptank River to Cambridge MD and the Little Choptank River. Eastern Bay. Patapsco River including Baltimore Harbor. At 320 PM EDT, Doppler radar indicated a group of showers, capable of producing winds to around 30 knots. These showers were located near Annapolis, moving east at 20 knots.

* WHAT. Heat index values 100 to 104 expected. * WHERE. Adams, Cumberland, Dauphin, Franklin, Lancaster, Lebanon, Perry, and York Counties. * WHEN. From noon Thursday to 8 PM EDT Friday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses. Heat-related impacts are likely in some health systems, heat-sensitive industries and infrastructure.