Southeast to south winds will occasionally gust to around 20 knots through late evening over the Lower Tidal Potomac River and middle Chesapeake Bay. Inexperienced mariners, especially those in small craft, should exercise caution and be prepared for locally higher winds and waves.

The New Jersey Department of Environmental Protection has issued a code orange air quality alert Thursday for Southwestern New Jersey. 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.state.nj.us/dep/

* WHAT. For the Heat Advisory, heat index values ranging from 95 to 100 degrees. For the Excessive Heat Watch, dangerously hot conditions with heat index values ranging from 100 to 105 degrees possible. * WHERE. Portions of northern Delaware, central, northern, and southern New Jersey, and southeast Pennsylvania. * WHEN. For the Heat Advisory, until 6 AM EDT Saturday. For the Heat Advisory, the hottest temperatures and heat indices are forecast to occur on Friday. For the Excessive Heat Watch, from Saturday morning through Sunday evening. * IMPACTS. Heat related illnesses increase significantly during extreme heat and high humidity events.