JANESVILLE, Wis. -

The coroner's office in Rock County said the death of an elderly woman was heat-related.

The coroner was called Thursday to the residence on East Godfrey Road in Lima Township where the woman was found dead.

Maragaret Jurgans, 83, died from a cardiac-related condition with the heat playing a major role in her death, according to the Rock County Coroner's Office. Jurgans' sister also lives in the residence, which authorities said was 95 degrees inside. The refrigerator was also broken, so authorities said there was no way to get cold liquids, either. Jurgans' sister was fine and remained at the home, according to the coroner's office.

Deputy Coroner Lou Smit said many people do not recognize the signs of heat-related illnesses until it is too late.

"You'll notice weakness, exhaustion, headaches, dizziness, disorientation, severe thirst, and dry mouth. Those are all precursors you aren't hydrated enough," said Smit. 

Temperatures have reached and even surpassed 100 degrees in much of Wisconsin the last several days.

The National Weather Service extended an excessive heat warning for much of the southern and western part of the state until Saturday. Dane County is under the warning until 7 p.m. Saturday.

In Madison, officials at UW Hospital and Clinics said about 50 people have been treated for dehydration, dizziness and other heat-related symptoms over the last few days.

St. Mary's Hospital said more than 80 patients have been treated for heat-related issues over the last four days at its facilities.

Stay tuned to WISC-TV and Channel 3000 for continuing coverage.