* WHAT. Heat index values up to 105. * WHERE. Atlantic, Cumberland, and Salem Counties. * WHEN. Until 8 PM EDT Wednesday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses.

* WHAT. Heat index values up to 104. * WHERE. In New Jersey, Morris, Sussex, Warren, and Hunterdon Counties. In Pennsylvania, Berks, Lehigh, Northampton, Upper Bucks, Western Chester, and Western Montgomery Counties. * WHEN. Until 8 PM EDT Wednesday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses.

* WHAT. Heat index values up to 104. * WHERE. Portions of northern Delaware, central, northern, and southern New Jersey, and southeast Pennsylvania. * WHEN. Until 8 PM EDT Wednesday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses.

Patchy fog late tonight is reducing visibilities adjacent to the coast, including near and along Garden State Parkway, down to one mile or less at times. Be prepared for rapid changes in visibility over short distances! Turn on your low-beam headlights and leave extra space between you and the vehicle in front of you. Fog is expected to linger through Tuesday morning.

* WHAT. Heat index values up to 105. * WHERE. Atlantic, Cumberland, and Salem Counties. * WHEN. Until 8 PM EDT Wednesday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses. * ADDITIONAL DETAILS. Peak heat indices on Wednesday are forecast to reach or exceed 100 degrees, and therefore an extension of this heat advisory into Wednesday is possible.

* WHAT. Heat index values up to 104. * WHERE. In New Jersey, Morris, Sussex, Warren, and Hunterdon Counties. In Pennsylvania, Berks, Lehigh, Northampton, Upper Bucks, Western Chester, and Western Montgomery Counties. * WHEN. Until 8 PM EDT Wednesday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses. * ADDITIONAL DETAILS. Peak heat indices on Wednesday are forecast to reach or exceed 100 degrees, and therefore an extension of this heat advisory into Wednesday is possible.

* WHAT. Visibility one quarter mile or less in dense fog. * WHERE. In Delaware, Delaware Beaches County. In New Jersey, Eastern Monmouth, Atlantic Coastal Cape May, Coastal Atlantic, and Coastal Ocean Counties. * WHEN. Until 10 AM EDT Tuesday. * IMPACTS. Low visibility could make driving conditions hazardous.

* WHAT. Heat index values up to 104. * WHERE. Portions of northern Delaware, central, northern, and southern New Jersey, and southeast Pennsylvania. * WHEN. Until 8 PM EDT Wednesday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses. * ADDITIONAL DETAILS. Peak heat indices on Wednesday are forecast to reach or exceed 100 degrees, and therefore an extension of this heat advisory into Wednesday is possible.

* WHAT. For the first Heat Advisory, heat index values up to 105. For the second Heat Advisory, 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. For the first Heat Advisory, until 8 PM EDT this evening. For the second Heat Advisory, from noon to 8 PM EDT Tuesday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur. * ADDITIONAL DETAILS. Overnight conditions will remain warm and humid so continue to find ways to stay cool and hydrated.

* WHAT. Dense fog will reduce visibility to 1 NM or less. * WHERE. Coastal waters from Sandy Hook to Little Egg Inlet NJ out 20 nm. * WHEN. Until 10 AM EDT Tuesday. * IMPACTS. Low visibility will make navigation difficult.

The Delaware Valley Regional Planning Commission has issued a code orange air quality alert Tuesday for The Philadelphia Metro area. 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 http://www.phila.gov/health/units/ams/