Locally dense fog will likely develop this evening into tonight. Visibilities could be reduced to a quarter mile or less at times. Locations along the immediate coast are most likely to see the dense fog. Motorists should be prepared for quickly changing visibilities. Slow down, allow for extra space between vehicles and use your low beam headlights in the fog.

The Massachusetts Department of Environmental Protection has issued an Air Quality Alert for Ground Level Ozone, from 11 AM to 11 PM EDT Tuesday. An Air Quality Alert means that Ground Level Ozone concentrations within the region may approach or exceed levels that are Unhealthy for Sensitive Groups. Air is unhealthy for sensitive children and adults, such as those with asthma, lung or heart disease, and older adults. Sensitive children and adults should limit prolonged outdoor activity. For additional information, please visit the Massachusetts Department of Environmental Protection website at: https://mass.gov/orgs/massachusetts-department-of-environmental- protection

* WHAT. Heat index values up to 100. * WHERE. In Connecticut, Northern Fairfield, Northern Middlesex, Northern New Haven, Northern New London, Southern Fairfield, and Southern New Haven Counties. In New York, Northern Nassau and Northwest Suffolk Counties. * WHEN. Until 8 PM EDT Tuesday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses. * ADDITIONAL DETAILS. An extension of this advisory into Wednesday may be needed.

* WHAT. Heat index values up to 99. * WHERE. Portions of northern Connecticut, central, eastern, southeastern, and western Massachusetts, and northern Rhode Island. * WHEN. Until 8 PM EDT Tuesday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses.