* WHAT. Heat index values up to 105 expected. * WHERE. In Maryland, St. Marys, Calvert and Extreme Western Allegany Counties. In West Virginia, Western Mineral County. * WHEN. From 11 AM to 8 PM EDT Saturday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur. * ADDITIONAL DETAILS. Oppressive heat and humidity will overspread the area Saturday and last into Sunday. Little relief from the heat is expected Saturday night with low temperatures in mid 70s to near 80 for most, which will compound heat stress on those without air conditioning.

* WHAT. Heat index values up to around 105 to 107 expected, with heat index values generally between 100 and 104 degrees west of the Blue Ridge Mountains. * WHERE. Portions of central, north central, northeast, northern, southern and western Maryland, The District of Columbia, central, northern and northwest Virginia and eastern and panhandle West Virginia. * WHEN. From 11 AM to 8 PM EDT Saturday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur. * ADDITIONAL DETAILS. Oppressive heat and humidity will overspread the area Saturday and last into Sunday. Little relief from the heat is expected Saturday night with low temperatures in mid 70s to near 80 for most, which will compound heat stress on those without air conditioning.

The Maryland Department of the Environment has issued a Code ORANGE Air Quality Alert Saturday for Northern Baltimore. 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 mde.maryland.gov/programs/air/AirQualityMonitoring/Pages/index.aspx.

The Maryland Department of the Environment has issued a Code ORANGE Air Quality Alert Saturday for the Baltimore City Metro and Annapolis region. 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 mde.maryland.gov/programs/air/AirQualityMonitoring/Pages/index.aspx.

* WHAT. South winds 10 to 15 kt with gusts up to 20 kt expected. * WHERE. Chesapeake Bay and adjoining estuaries north of Smith Point VA, and Tidal Potomac from Cobb Island MD to Smith Point VA. * WHEN. From 4 PM this afternoon to 2 AM EDT Saturday. * IMPACTS. Conditions will be hazardous to small craft.

* WHAT. Maximum heat index values 100-102 Friday afternoon. Maximum heat index values 102-104. Maximum heat index values 100-103 Sunday afternoon. * WHERE. A portion of central Pennsylvania. * WHEN. Until 8 PM EDT Sunday. * IMPACTS. Hot temperatures and high humidity may cause an increase in heat-related illnesses. * ADDITIONAL DETAILS. The risk of heat-related impacts is expected to reach its highest level over the weekend. The early arrival of the heat in the summer season, persistence of heat over multiple days, and very warm nights will be aggravating factors of overall heat stress.

* WHAT. Heat index values up to around 105 to 107 expected, with heat index values generally between 100 and 104 degrees west of the Blue Ridge Mountains. * WHERE. Portions of central, north central, northeast, northern, southern and western Maryland, The District of Columbia, central, northern and northwest Virginia and eastern and panhandle West Virginia. * WHEN. From 11 AM to 8 PM EDT Saturday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur. * ADDITIONAL DETAILS. Oppressive heat and humidity will overspread the area Saturday and last into Sunday. Little relief from the heat is expected Saturday night with low temperatures in mid 70s to near 80 for most, which will compound heat stress on those without air conditioning.