The San Juan National Forest in southwestern Colorado will shut down for the first time in its 113-year history as the drought-driven 416 fire has climbed to 22,131 acres.

The closure order was signed Monday night and the shutdown will become effective Tuesday. It will prohibit entry by the general public into the 1.8 million-acre forest, across nine counties, at the start of the area’s busy summer season, which attracts worldwide visitors and tourists.

The SJNF implemented Stage 1 fire restrictions on May 1 followed by Stage 2 fire restrictions on June 1, but conditions continue to deteriorate as the 416 fire and the 1,000-acre Burro fire continue to grow.

“Under current conditions, one abandoned campfire or spark could cause a catastrophic wildfire, and we are not willing to take that chance with the natural and cultural resources under our protection and care, or with human life and property,” said Richard Bustamante, SJNF forest fire staff officer.

The closure order will remain in effect until the forest receives sufficient moisture to improve conditions.

[ Map: Wildfires in Colorado and the United States ]

The National Weather Service forecast for the area includes a chance of thunderstorms and showers from Thursday through Sunday, but that likely won’t bring enough moisture to reopen the forest, said Cam Hooley, SJNF spokeswoman.

“The weather at the end of this week is probably not anything big enough to make much of a difference,” Hooley said. “It will all be based on the weather; my best guess is whenever the monsoon moisture arrives, we’ll be able to get out of the closure.”

The monsoon season in southwestern Colorado typically pops in mid-July.

Exceptions to the full-out closure will be made for people who own property within the forest, and for ranchers who graze cattle on forest lands. Both property owners and ranchers will have to contact forest managers and make arrangements to enter and use the forest, Hooley said.

McPhee Reservoir, northwest of Dolores and along a southwest edge of the SJNF border, will remain open, Hooley said. All forest service roads, trails, campgrounds and campsites, however, will be closed.

“Forest campgrounds, day use areas, roads, and trails will be closed, including wilderness areas … hiking, dispersed camping, and other recreational activities are prohibited,” officials said in a news release. “The McPhee Recreation Area Complex boat ramp and marina will likely remain open but no shoreline use will be allowed.”

Firefighters working through Sunday night stopped the advance of the 416 fire at the boundary of the town of Hermosa Creek, saving hundreds of homes even as the wildfire continued to grow to a total of 22,131 acres, authorities say.

“The fire burned right up to the edge of Hermosa,” said Shawn Bawden, fire spokesman. “We’re happy to say no one has been injured and no homes have been burned. It speaks to the professionalism of the firefighters.”

The wildfire had nearly doubled in size on Sunday to 17,000 acres and was advancing at the rate of one mile an hour until it reached fire lines built by hundreds of firefighters, Bawden said. A total of 813 firefighters are now fighting the 416.

The advancing fire, burning about 13 miles north of Durango, triggered mandatory evacuations of 675 homes Sunday, including some at Purgatory Resort. The total number of homes covered by the evacuation orders is now around 2,200.

The fire was only about 15 percent contained, Bawden said.

“This is rugged, remote country,” he said. “Firefighters are working hand lines straight up the mountain.”

In Durango, a southern gateway to the SJNF, between 800,000 to 1 million tourists typically use the city as a springboard to the forest’s recreational activities during the summer season.

“We were full starting on Memorial Day; now, that is tapering off,” said Frank Lockwood, executive director of the Durango Area Tourism Office.

When the 416 fire was first reported, on June 1, about 10 miles north of Durango, the sentiment in town was: “Hey, we are open for business; you can still do everything,” Lockwood said.

But the 416 fire quickly grew as prolonged dry conditions in the area continued and the fire burned through tinder-dry fuels.

“So much for the hiking trails; now, that’s done,” Lockwood said.

Smoke from the 416 fire has been drifting in downtown Durango during the morning hours. Hoteliers have been telling Lockwood that visitors are starting to cancel reservations. “We may be down from 15 to 20 percent,” he said.

The Colorado Department of Public Health and Environment has issuing air quality health advisories because of the wildfire smoke for Durango and surrounding areas including Alamosa and Pagosa Springs.

Should cancellations multiply, and the forest closure be extended for months, tourism losses for Durango and other southwestern Colorado towns will be in the millions.

“We don’t know what we’re going to need to do to recovery,” Lockwood said. “But the people in Durango are strong. We will pull together and recover. We just don’t know when.”