Fog will continue to develop through the early morning hours with some of it becoming dense, reducing visibilities to a quarter mile or less. Locations right along the immediate coast will be more likely to experience 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. A Dense Fog Advisory may be needed should the dense fog become widespread.

* WHAT. Heat index values up to 97 expected. * WHERE. In Connecticut, Hartford CT, Tolland CT, and Windham CT Counties. In Massachusetts, Southern Worcester MA, Central Middlesex MA, Western Norfolk MA, Northern Bristol MA, and Western Plymouth MA Counties. In Rhode Island, Northwest Providence RI and Southeast Providence RI Counties. * WHEN. From noon Monday to 8 PM EDT Tuesday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses.

The very humid conditions continue overnight, and will lead to more areas of fog. Patchy dense fog is expected, reducing visibility to one quarter mile or less in spots. Travelers should be prepared for rapid drops in visibility. Slow down and allow extra time to reach your destination safely.

* WHAT. Heat index values of 95 to 100 expected. * 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. From noon Monday to 8 PM EDT Tuesday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses. * ADDITIONAL DETAILS. The highest heat index values will be generally in the afternoon and early evening hours.