It is reportedly common for students at the university to climb the Keating Hall clock tower, touch the bell and take photos of the NY city skyline from outside one of its windows before they graduate.
New York Police Department arrived on the scene and found her lying on the ground with trauma to her head and body.
Ms Monfries' family rushed to her hospital bed and were accompanied by two priests, the Post reported. The tower is off limits to students and university officials are investigating how the students gained access to the tower.
On Sunday night, the university released a statement saying, "Our hearts go out to Sydney's parents, and her family and friends".More news: Here's a look at the Xbox One S All-Digital Edition
Monfries and a group of friends climbed the tower at roughly 3 a.m.
Access to the tower is restricted, a university spokeswoman told the Times.
A female student at Fordham University in the Bronx is in serious condition after falling from the school's bell tower in Keating Hall. Some students said the incident happened during a senior student tradition. During the event, seniors climb the tower, touch the bell and take photo outside one of the top windows. "If he wasn't there, I don't know, she might have been worse off", he said.
Sydney was studying journalism and interned at InStyle magazine - being set to graduate in May.More news: Bharat first look poster out: Salman Khan in never-seen-before avatar
School president Joseph McShane confirmed the tragic news in a letter to students later that evening. "Theirs is an unimaginable loss, and we share their grief".
The school said Monfries will get receive her bachelor's degree posthumously.
According to the university's website, Fordham University is a Jesuit, Catholic institution focused on instilling students with "wisdom, experience, morality, critical thinking and creative problem-solving".More news: Finnish Social Democrat leader Rinne declares victory in election