Stewart sustained a broken right tibia and fibula in a violent wreck Monday night at Southern Iowa Speedway in Oskaloosa, Iowa, team officials confirmed.
Stewart was transported by ambulance to a local hospital then airlifted to another facility in Des Moines, where he underwent surgery early Tuesday morning.
The wreck is Stewart’s third in a Sprint car in as many weeks.
According to a team release, Stewart’s planned test Tuesday at Atlanta Motor Speedway has been canceled.
Stewart will also miss Sunday’s Sprint Cup Series race at Watkins Glen (N.Y.) International but a replacement driver has not been immediately named.
Additional information is expected Tuesday afternoon, the statement said.
Compound lower leg fractures with cast immobilization typically require 12 to 16 weeks of healing time. A period of rehabilitation is generally required as well.
There are 15 races left in the 2013 Sprint Cup Series season. After his ninth place finish in Sunday’s race at Pocono (Pa.) Raceway, Stewart was 11th in the series standings.
There are five races remaining before the 12-driver Chase for the Cup field is set. As of now, Stewart would have qualified for one of the two wild card spots.
Once Stewart sits out a race, he’ll lose likely any chance at making the Chase this season.
Just this past weekend, Stewart offered a vigorous defense of his frequent visits to dirt tracks across the country in addition to his NASCAR obligations.
Stewart barrel-rolled his car several times last week in wreck in a Sprint car race in Ontario, Canada.
“You guys need to watch more sprint car videos and stuff. It was not a big deal,” Stewart said at Pocono. “It's starting to get annoying this week about that, so that was just an average sprint car wreck. When they wreck they get upside down like that. That was not a big deal.”