Charleston County school leaders say they did everything in their power to get James Simons Elementary to start the 2013-14 school year in its new downtown building, but they couldn’t control the weather.

Frequent and sometimes heavy rain has prevented construction workers from meeting a June 11 deadline to have the building “dried in,” or completely enclosed with air circulating. That means the school will open Aug. 21 at its temporary home, which is the former Brentwood Middle School in North Charleston.

The school will move into its new building downtown in October.

“This is disappointing, but it just is,” said Bill Lewis, the district’s chief operating officer. “We just can’t fight Mother Nature.”

The Charleston County School Board wanted the school to be finished for the first day, so it approved last month an undisclosed amount of money to accelerate construction work.

Work on the building will continue at an aggressive pace, but Lewis said he can’t guarantee an Aug. 21 finish date.

“That’s highly improbable,” he said. “We’re just running out of time.”

Lewis couldn’t pick a date the building would be ready because of uncertainty involving the weather, but he said the contractor has made good progress with good weather. Two of four sections of roofing have been completed, with the final and largest section still remaining.

James Simons Elementary is one of four downtown schools that had seismic deficiencies and are being rebuilt. The school board promised in 2010 that all four would be reopened by the start of the 2013-14 school year, and it is on track to make good on its promise with Buist Academy and Memminger Elementary.

Charleston Progressive Academy also will start the new school year in its new downtown building, but it will be another month before some of its campus is finished. James Simons Elementary had been about six months behind the other projects because its design was delayed until parents picked a new program focus, which will be Montessori. Officials have been trying to make up time since then.

Some board members, such as Todd Garrett, were worried that if James Simons started on its North Charleston campus, some parents who were new to the school might not enroll their children. The school will have about 200 students this year, and its enrollment is slated to roughly double this fall. That’s likely because of its new building and Montessori program.

“I was concerned because I thought ... we had this opportunity and we were going to scare parents off,” he said. “I still think it’s critical (to finish quickly), but my impression is that parents are less concerned than they were earlier. The tenor changed from the parents, as I understand it.”

Board members received word late last week that the building wouldn’t hit the June 11 target date, and the school since has been calling and sending letters to students’ parents.

Board Chairwoman Cindy Bohn Coats said the board wants to be updated on the progress of the building, and it wants to ensure that the opening is as smooth as possible for teachers and students.

“Nobody wants these kids back in downtown schools more than this board,” she said. “Everyone is anxious to have this successfully completed and behind us.”

Reach Diette Courrégé Casey at @Diette on Twitter or (843) 937-5546.