Forecast: Heat advisory issued for Wednesday and Thursday for LI

The National Weather Service has issued a heat advisory for Nassau and northwest Suffolk, warning of heat and humidity that will make it feel like it's in the upper 90s or higher.

The advisory is effective from Wednesday at noon to Thursday at 8 p.m. Tuesday's high was in the high 80s for most of Long Island, but temperatures will be going up from there.

Wednesday likely will be a hotter and steamier version of Tuesday, with the real-feel heat index between the mid and upper 90s. Thursday, the heat index goes up to between the high 90s and 100 degrees.

"Heat indices increase on Thursday with higher dewpoints on more of a southerly component flow," the weather service said, referring to the wind. "Some areas will approach 100."

That means the weather service advises, for those days, that seniors or anyone with a health issue stay inside air-conditoned places or seek cooling centers. The longer you stay outside or in a room without air-conditioning, there is more of a chance you will get heat-related illness, the advisory said.

The cloud-clearing high pressure system, sitting off Bermuda, will also sweep the humidity up from the South with its clockwise spin, depositing it on Long Island's doorstep.

The heat, along with abundant sunshine some may welcome after a weekend of stormy weather, will last through Friday, the weather service said.

There is a chance of a thunderstorm Thursday afternoon or evening that may make Friday a touch cooler as a cold front approaches.

The weekend will bring relief, with a high of just 80 degrees expected Saturday.

In the wake of what is now Tropical Depression Henri, there was a high risk of rip currents at beaches on Tuesday, "with the potential for flash rip activity due to Henri induced erosion," the weather service said.

The storm, now Tropical Depression Henri, left the region altogether Monday and is now reaching the Canadian Maritimes.