PORTLAND, Maine — While recent weather may suggest otherwise, it’s only a few months before the drama of professional baseball once again thrills Portland spectators.

But this spring, some of that drama will take place not at Hadlock Field, but in Merrill Auditorium.

“The Summer King,” an opera based on the life of Negro Leagues great Josh Gibson and written by Peaks Island resident Daniel Sonenberg, is scheduled to make its world premiere on May 8.

In December, the National Endowment for the Arts awarded Sonenberg a $15,000 grant to help stage the performance, which is sponsored by nonprofit performing arts group Portland Ovations. Production costs are expected to top $50,000.

The grant takes some financial pressure off Sonenberg and Ovations, although both continue to seek funding for the May concert performance. They also hope to attract backing to allow a more extensive production that would feature full staging, props and costumes.

Songs from the opera have already been performed at several concerts across the country, prompting a critic from The Wall Street Journal to write, “Mr. Sonenberg hears Gibson’s story in the musical language of grand opera.” Selections from “The Summer King” will also be presented next week at a professional music forum in New York City.

But the May concert will be the debut of the entire opera. And first, Sonenberg must finish orchestrating his composition; he needs to complete the remaining four of its 11 scenes by April.

“It’s going to be a bit of a mad dash,” he said in an interview last week.

Sonenberg, 43, teaches music at the University of Southern Maine and leads a local rock band, Lovers of Fiction. He began work on “The Summer King” in 2004, shortly before moving to Portland from New York.

“It’s hard to believe it’s been that long,” he said. “I guess [the time to compose the opera] has been a bit on the long side.”

With 14 principal roles, a score for a minimum of 16 musicians, and a performance time of more than two hours, “The Summer King” may be a “challenge to produce,” Sonenberg added. “But I don’t regret [the opera] becoming sort of an unwieldy thing. Sometimes you just have to write the piece you need to write.”

“The Summer King” tells the tragic story of Gibson, who is widely regarded as one of the greatest catchers and power hitters in the history of baseball. He played in Pittsburgh and Washington, D.C., during the 1930s and 1940s, the height of the Negro Leagues’ popularity.

But after suffering from drug problems and mental illness, he died in January 1947, just three months before Jackie Robinson broke the racial barrier in major-league baseball by playing for the Brooklyn Dodgers.

Gibson was nicknamed “the black Babe Ruth.” He was inducted into the National Baseball Hall of Fame in 1972 — only the second Negro Leagues player to be inducted, and the first never to have played in the major leagues.

“He led the charge,” Sonenberg, an avid baseball fan, said. “There never would have been a Jackie Robinson if people like Gibson hadn’t first made it apparent that there was this source of talent.”

Nevertheless, “baseball is almost incidental to the story,” he said. “This is a human story, an American historical story. You can think of it as a civil rights struggle that predated the civil rights era.”

Sonenberg compares Gibson to the Biblical story of Moses, who led his people from slavery to “the promised land,” but never entered it. The opera’s title alludes to that near-miss.

“Josh was the king of summer, but he did not get to enjoy autumn,” Sonenberg said. Such an epic, larger-than-life story is a fitting one for opera, he feels.

“In some ways, this story is almost too obviously operatic,” he said. “Opera is a medium that is not about subtleties. It has a way of indulging in intense emotions and allowing the audience to envelop themselves in the story … so this really plays well.”

While opera is also sometimes regarded as a sophisticated, high-brow medium, Sonenberg said he hopes “The Summer King” will be music everyone can enjoy. The opera echoes a potpourri of musical styles, including jazz of the time period and even the sound of a Mexican mariachi band.

Perhaps that variety is not surprising for a composer who teaches Beethoven but whose band plays “straight-forward, driving rock,” influenced by David Bowie and The Kinks.

“There are a lot of ways ‘in’ for listeners with different musical backgrounds. … At the end of the day, I wanted to present this story in a way that is emotionally accessible,” Sonenberg said. “The notion that certain genres are superior is nonsense. Good music is good music.”