The hot temperatures from Sunday will extend into today, becoming even more oppressive, according to the National Weather Service.

The National Weather Service has issued a heat advisory from 10 a.m. to 8 p.m. today for Central New York and Northeast Pennsylvania including Cortland, Chenango, Tioga, and Broome counties in New York and Bradford and Susquehanna counties in Pennsylvania.

The National Weather Service says we should prepare for "hot and muggy conditions" with the temperature hovering around 90 today and the possibility for very strong thunderstorms this afternoon and evening which may bring strong, gusty winds, and very heavy downpours. There’s also a chance for some isolated flash flooding.

So what is a heat advisory and why is it something we should pay attention to?

High temperatures paired with high humidity could bring a heat index of more than 100 degrees in some areas which can cause medical problems for some people. The National Weather Service explains that by issuing a heat advisory, hospitals and government officials are given advance warning of what may come and are better equipt to "prepare and respond to an increase in emergency calls, and activate programs to check on elderly and the home-bound. In some cases, cooling centers can be open or designated and donation programs activated for fans and air conditioners."

During a heat advisory, people who are sensitive to the heat, such as elderly people those with heart conditions, breathing problems, and infants should stay in air-conditioned areas if at all possible. If you have to work outside during a heat advisory, you should take precautions to stay properly hydrated. And remember, absolutely do not, for any reason, leave children or pets unattended in a vehicle.

This oppressive heat wave won't last long though. The heat and humidity are expected to taper off Monday night and then the weather will turn cooler by Tuesday when temperatures will dip to around 80 degrees.