Authorities say the death of a 5-month-old girl who was left in a sweltering minivan all day appears to be a tragic accident. A university professor who tracks such deaths says it's a tragedy repeated many times each year.

Kate Boe, who died Wednesday in Grand Forks, is the eighth child to die this year in the United States after being left - and oftentimes forgotten - in a hot vehicle, said Jan Null, a professor of meteorology at San Francisco State University.

"It's very hard to fathom that someone could do this," Null said. "But if you look at the numbers, it's not uncommon."

Andrea Boe, 34, thought she had left her daughter at a day care center before going to work Wednesday morning, authorities said. Police said the mother drove to her day care about 5:30 p.m., after leaving work, and was told she had not dropped the girl off earlier.

Police said the child was in a car seat in the back of the vehicle.

"It appears at this point that the mother simply forgot the child in the van," Police Lt. Rahn Farder said.

Farder said an autopsy was being done Thursday. He said no charges are expected to be filed.

"Basically, it appears that this was a tragic accident, but we will be conducting a standard investigation," Farder said. "We don't anticipate anything, but we want to make sure."

Null, a retired U.S. Weather Service meteorologist, said 298 such deaths have been recorded since 1998. The child's death on Wednesday was North Dakota's first, he said. Only six states have not had at least one such death since 1998, he said.

"In 39 percent of the cases, it appears that the parent forgot about the child for one reason or another," Null said.

The high temperature in Grand Forks on Wednesday was 78 degrees, according to the National Weather Service. The National Highway Traffic Safety Commission says temperatures easily can climb to more than 100 degrees within minutes in an enclosed car.