Conditions were ripe for what has become New Jersey’s biggest wildfire since 2007: freakishly low humidity, high winds, dry tinder, crowds on a holiday weekend — and an illegal campfire that possibly lit the fuse.

The Wharton State Forest wildfire had consumed about 13,500 acres, with many popular recreation areas still closed, according to officials from the New Jersey Forest Fire Service. The state forest is often referred to as the heart of the 1.1 million Pinelands National Reserve.

The fire, which was first reported Sunday at 10 a.m., was about 95% contained as of Tuesday night.

Greg McLaughlin, chief of the New Jersey Forest Fire Service, who noted that crews have been working nonstop to battle back the blaze, said during a press conference earlier Tuesday that, “we’re confident that the fire is not going to escape.”

McLaughlin said 75 firefighters were still at the scene with 22 fire engines, a helicopter, and other specialized equipment as of Tuesday afternoon. A NASA fire map showed the stretched about 8 miles long and 4 miles wide.

“They’ll continue to be there for several days, if not a week, or until we get significant rainfall,” McLaughlin said. The National Weather Service is predicting a chance of showers off and on through Thursday.

Officials have ruled out a lightning strike, or other natural phenomena, as a cause, and are focusing on an “illegal unattended campfire” in a remote area of Wharton, New Jersey’s largest state park.

Two major roads, Routes 206 and 542, which had been closed since the fire was first reported are now open.

But Batsto Village, Atsion Recreation Area, Mullica River Campground, and Lower Forge Campground all remain closed. Nearby hiking and biking trails are closed as are kayak and canoe launches along the Mullica River. Pinelands Adventures has suspended its paddling trips.

Although 18 structures were threatened, all remain intact. There have been no injuries reported. In comparison, the Warren Grove fire in 2007 burned 17,000 acres and destroyed four homes, while damaging more than a dozen others.

Some facilities should be open within 24 hours, but hiking and biking trails will likely remain closed longer until they can be inspected, officials said. Because the winds have been blowing west to east, smoke has been drifting toward the Atlantic Ocean.

The fire began on what was a busy few days for hikers, bikers, and paddlers as Father’s Day and Juneteenth both fell on Sunday. Friday was the state-observed holiday for Juneteenth, so many people were off for a long weekend. Wharton State Forest has long been a mecca for lovers of the outdoors.

The 110,000-acre state forest was named after Philadelphia industrialist Joseph Wharton, who purchased property in the area in 1876 that contained Batsto Village, where iron was made for the American Revolution, and a mansion. The forest also contains the popular Atsion Recreation Area, Oswego Lake, a major chunk of the Batona Trail, and the Carranza Memorial, which commemorates the spot where Captain Emilio Carranza Rodríguez was killed during what was then a historic flight from Mexico City in 1928.

It’s also popular with kayakers on the Mullica River, which bisects the park. It lies about 20 miles northwest of Atlantic City, and 40 miles southeast of Philadelphia.

Officials said someone, or a group of people, in a remote area lit a “makeshift fire” not in a designated camping area. However, officials don’t know whether the person who started the fire was camping or just passing through.

Although officials were still not sure Tuesday that the campfire was the origin, a blaze within the forest was spotted from the Batsto fire tower at 10 a.m. Sunday. It had grown to about 50 acres before crews arrived and managed to penetrate the thick brush with specially designed trucks. Wind gusts were reaching 30 mph and, McLaughlin said, “very low humidity” helped to prime and pump the flames.

The Pine Barrens contain lots of downed trees and dried pine needles that act as fuel.

Crews called in a helicopter to drop water from Atsion Lake.

As the blaze intensified, about 50 people had to be evacuated from Paradise Lake Campground in Hammonton, as well as a few people from other areas.

Bill Caruso, 48, a lawyer from Berlin, Camden County, said he was kayaking on the Mullica River when the fire started to rage.

“The wind was up to 30 mph and it was casting smoke downstream,” said Caruso, who’s paddled the river for around two decades and is a member of the South Jersey Kayakers. “I saw a helicopter dip its bucket in a lake nearby to fill it with water to fight the fire.”

Caruso, who usually paddles several times a week, isn’t sure when he can return to the waters that bring him peace.

“We’re living in one of the most highly populated areas in the free world, and here is this little gem with tree-covered water the color of tea, in a remote wilderness that’s just beautiful,” he said. “You see bald eagles, deer, bears, coyotes. It’s just gorgeous.”

Several people staying at the Belhaven Lake RV Resort in Egg Harbor Township left over the last few days because of smoke and ash, said a woman who helps run the place who identified herself only as Selena.

”Members were very concerned because the fire was less than four miles away,” she said. ”They didn’t want to turn on their air conditioners and bring in whatever was in the air, so they just went home.”

Bob Williams, who owns Pine Creek Forestry in Deptford, Gloucester County, has been a frequent critic of the state’s handling of the Pine Barrens, warning for years that it is a tinderbox. Climate change has only made the situation more urgent, he said.

However, he also says that fires are beneficial to the unique ecology of the Pine Barrens.

“Pitch pine is a very fire adaptive ecosystem,” Williams said. “It opens up the understory for a variety of plants that wait for fire to regenerate.”

This story has been corrected to say Captain Emilio Carranza Rodríguez died in 1928.