* WHAT. Heat index values up to 107 expected. * WHERE. In Maryland, Cecil, St. Marys, Calvert and Southeast Harford Counties. In Virginia, Orange, Culpeper, King George and Southern Fauquier Counties. * WHEN. From noon to 8 PM EDT Friday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur. * ADDITIONAL DETAILS. The combination of air temperatures in the 90s and high humidity will result in the potential for increased heat-related illnesses.

* WHAT. For the first Heat Advisory, heat index values up to 100. For the second Heat Advisory, heat index values up to 106 expected. * WHERE. Portions of central, northern and southern Maryland, The District of Columbia and central and northern Virginia. * WHEN. For the first Heat Advisory, until 8 PM EDT this evening. For the second Heat Advisory, from noon to 8 PM EDT Friday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur. * ADDITIONAL DETAILS. The combination of air temperatures in the 90s and high humidity will result in the potential for increased heat-related illnesses, especially those partaking in outdoor Independence Day activities today.

The areas affected include. Chesapeake Bay from Pooles Island to Sandy Point MD. Chesapeake Bay from Sandy Point to North Beach MD. Chesapeake Bay north of Pooles Island MD. Chester River to Queenstown MD. Eastern Bay. Patapsco River including Baltimore Harbor. At 558 PM EDT, Doppler radar indicated a gust front, capable of producing winds of 20 to 30 knots. This front was located along a line extending from 16 nm northwest of Middle River to 10 nm west of Fort Smallwood Park to 6 nm northwest of Chesapeake Beach, moving east at 20 knots.

* WHAT. Heat index values up to 107 expected. * WHERE. Portions of central, north central and northern Maryland, central, northern, northwest and western Virginia and panhandle West Virginia. * WHEN. From noon to 8 PM EDT Friday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur. * ADDITIONAL DETAILS. The combination of air temperatures in the 90s and high humidity will result in the potential for increased heat-related illnesses.

* WHAT. Heat index values up to 108 expected. * WHERE. In Maryland, Cecil, St. Marys, Calvert and Southeast Harford Counties. In Virginia, Orange, Culpeper, King George and Southern Fauquier Counties. * WHEN. From noon to 8 PM EDT Friday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur. * ADDITIONAL DETAILS. The combination of air temperatures in the 90s and high humidity will result in the potential for increased heat-related illnesses.

* WHAT. For the first Heat Advisory, heat index values up to 100. For the second Heat Advisory, heat index values up to 109 expected. * WHERE. Portions of central, northern and southern Maryland, The District of Columbia and central and northern Virginia. * WHEN. For the first Heat Advisory, until 8 PM EDT this evening. For the second Heat Advisory, from noon to 8 PM EDT Friday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur. * ADDITIONAL DETAILS. The combination of air temperatures in the 90s and high humidity will result in the potential for increased heat-related illnesses, especially those partaking in outdoor Independence Day activities today.

The Virginia Department of Environmental Quality has issued a Code ORANGE Air Quality Alert Thursday for Northern Virginia. A Code Orange Air Quality Alert means that air pollution concentrations within the region may become unhealthy for sensitive groups. Sensitive groups include children, people suffering from asthma, heart disease or other lung diseases and the elderly. The effects of air pollution can be minimized by avoiding strenuous activity or exercise outdoors. For more information on ground-level ozone and fine particles visit the web site Virginia DEQ air quality web site at www.deq.virginia.gov.

The Metropolitan Washington Council of Governments and District Department of Environment has issued a Code ORANGE Air Quality Alert Thursday for the District of Columbia. A Code Orange Air Quality Alert means that air pollution concentrations within the region may become unhealthy for sensitive groups. Sensitive groups include children, people suffering from asthma, heart disease or other lung diseases and the elderly. The effects of air pollution can be minimized by avoiding strenuous activity or exercise outdoors. For more information on ground-level ozone and fine particles visit the web site https://www.mwcog.org/environment/air/forecast/.