The Snowdonia stained glass was one of the first of its kind in the deep South to include a black Saviour.
It was gifted to the 16th Street Baptist Church in Birmingham following the 1963 Ku Klux Klan bombing that killed four girls and destroyed most of the church.
Welsh artist John Petts designed and created the window, following the racially motivated attack and collected donations from thousands of Welsh locals to finance it.
Ted Debro, a tour guide at the church, told the BBC: "This window is an important window and piece of art so the window can never really be replaced.
"The threat is that if some of the storms that have been coming through Alabama here of late can come in and really destroy the window.
"It's an important indication for the entire world of love and reconciliation and it's recognised throughout the world as an important symbol of the movement, of Christs' love and as a commitment from God to his people."
The church is appealing to the public to raise funds to protect the window from the storms forecasters have predicted are heading to the city.
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