“The Soul Queen of New Orleans” is sitting on a squeaky black leather couch in the television room of her newly renovated home in New Orleans East. Everything is echoey and new: the pink marble floors, freshly painted peach walls, every stick of furniture, a boxy flat-screen TV wedged into a corner, and the sparkly gold and crystal chandelier that dangles over our heads. A freshly cleaned swimming pool twinkles through the glass sunroom off the rear of the house, and in the living room stacks of cardboard boxes filled with furniture await assembly.

Irma Thomas and her husband Emile Jackson have only recently settled back into their home after the post–Hurricane Katrina flooding submerged their neighborhood. They had been staying in Gonzales, Louisiana, near Baton Rouge, while they worked on getting their home back in shape. Before the storm, the now-sixty-seven-year-old Thomas was set to record her seventeenth album at the legendary Ultrasonic Studios in New Orleans. But like so much of the city’s musical history, Ultrasonic was washed away in the floods, so Thomas and her producer pulled the best area musicians into Dockside Studio in rural Maurice, Louisiana, and laid down After the Rain, which just may be the best record of Thomas’ nearly fifty-year career.

The Recording Academy agreed, awarding the album a Grammy last year, Thomas’s first (after two prior nominations, in ’91 and ’98). On After the Rain, there are no horns, so her voice is more on display than ever, and unlike many singers whose instruments get thrashed as the years roll on, Thomas’s voice has only refined with age. She has been called the best female R&B vocalist of all time, albeit one who didn’t have the industry push that folks like Aretha Franklin, Gladys Knight, Dionne Warwick, and Tina Turner had.

Thomas started singing as a teen in her church choir, and by age twenty she had four children and was twice divorced. While waitressing at New Orleans’s Pimlico Club in the late ’50s, she occasionally sat in with bandleader Tommy Ridgely, who helped set her on the path to recording her first hit single, “You Can Have My Husband (But Don’t Mess With My Man),” in 1960. The song reached No. 22 on the Billboard R&B chart, setting in motion a slew of recordings for Minit (later Imperial) Records, including charters like “It’s Raining,” “Ruler of my Heart,” “Wish Someone Would Care,” and “Time Is on My Side” (well before the Rolling Stones bit her take in their cover of the song).

Thomas has reached that rare point in a life where memoir is actually appropriate—if a little overdue. Two women affiliated with local...