The night before one of Jane Fonda’s recent arrests, a member of her social media team asked if she would consider writing a letter from jail.

“With what?” Fonda replied. “I’ll be without my phone.” She paused a beat, “Or adult diapers.” Also, Fonda continued, musing out loud, it was one thing for the Rev. Martin Luther King Jr. to write a letter from jail. But her? The plan was nixed.

Fonda, who is 81, moved to Washington in September to highlight the urgency of the climate crisis by staging protests at the Capitol. Wrapped in a bright red coat, she has been arrested every Friday for the past four weeks, often with a famous friend or two in tow: Sam Waterston, Ted Danson, Catherine Keener and Rosanna Arquette.

Fonda plans to keep protesting until mid-January, when production of her Net­flix show, “Grace and Frankie,” resumes. In fact, she expects to turn 82 in jail, on Dec. 21.

Fonda is hale, but being arrested at her age brings challenges, like staying balanced with bound hands while clambering into a police wagon. After spending a night in jail and using her coat as a mattress, she told the Washington Post that her bones hurt.

Celebrity protesters make for soft targets, and Fonda said that there was no question she has benefited from her white privilege and fame, but said she was protesting out of a need to do more.

“Why be a celebrity if you can’t leverage it for something that is this important?” she said.

She hopes to inspire others to flood the streets and compel lawmakers to force fossil fuel companies to keep trillions of dollars of remaining oil reserves in the ground.

Whether this lofty goal is reached, she has at the least made pop culture inroads. Her recent acceptance of a Bafta Award while getting arrested went viral, and Buzzfeed’s suggested Halloween couples costumes included dressing as Fonda and her arresting officer.

Her demonstrations and arrests now are productions unto themselves. There are speakers and musicians, weekly topics (the ocean, women, militarization) and, each Thursday night, an hourlong teach-in that is streamed live on Facebook.

The protest-and-arrest plan began to take shape over Labor Day, when she was vacationing in Big Sur with Keener and Arquette. Fonda had been fighting what she described as deep-seated physical malaise and depression that she ascribed to ever-worsening climate news.

That weekend, she was reading an advance copy of Naomi Klein’s new book, “On Fire: The (Burning) Case for a Green New Deal,” and it hit her like a lightning bolt. “It was just cooking, cooking, and then she was on the phone,” recalled Keener (who worked with Fonda and Arquette on the 2012 film “Peace Love & Misunderstanding”).

During a conference call with Klein, Annie Leonard, executive director of Greenpeace USA, and environmental activist Bill McKibben, the plan was born. They called the events Fire Drill Fridays, inspired by Swedish teenage climate activist Greta Thunberg’s cri de coeur, “Our house is on fire.”

The plan called for protesters to wear red, and Fonda said her new coat, bought on sale at Neiman Marcus, would be the last item of clothing she would ever buy, because she does not need more stuff.

“I think she took just the right message from the example of the young school strikers,” McKibben wrote in an e-mail. “It’s good that kids are leading, but it’s not OK to take the biggest problem on Earth and assign it to 15-year-olds.”

There have been hitches. Moving to Washington, D.C., meant missing time with her 3-month-old grandson. And Fonda’s plans to bring along her dog, a 15-year-old Coton de Tulear named Tulea that she describes as her “soul mate,” were scotched after the dog became too ill to fly.

There was also the matter of “Grace and Frankie.” Production of the show’s final season is scheduled to begin in January, so Fonda asked Ted Sarandos, the chief content officer of Netflix, if it could be delayed for one year. Sarandos said no. (The exchange was confirmed by Netflix.) Fonda also had several speaking commitments related to the show. “I tried to get out of everything, but I couldn’t because I signed contracts,” she said.

On a recent morning in D.C., a church basement near the Supreme Court was filled with dozens of Fire Drill Friday protesters eating pastries, drinking coffee and strategizing.

After finishing an interview with NPR, Fonda, wearing her red coat and a tilted olive fedora, flitted among them like a mother bird, delivering greetings and hugs. Then they marched toward the Capitol, Fonda leading the way, camera crews and other journalists hustling to keep up.

A stage with a Fire Drill Fridays backdrop was set up on the lawn, and among the hundreds gathered were alumni from Fonda’s high school, the Emma Willard School in Troy, N.Y.; members of Elders Climate Action, and someone dressed in a plush polar bear costume.

Fonda greeted them all, and invited up speakers; among them Keener, Arquette (“Every human life depends on honoring our planet”) and Fonda’s close friend playwright Eve Ensler, who recited a poem about the Earth that left listeners misty-eyed. Then it was off to the Senate building, where, shortly before her arrest, Fonda was asked if her civil disobedience was having its intended effect.

“You are all here,” she said, indicating the swarm of camera crews and journalists. “So I think it’s working.”