And he wants to make the most of it.
"Being in a race and having something to pitch for the last week of the season -- that's what it's all about," he said. "We need wins and I'm going to work hard to try and get one."
Jackson (12-9) was acquired from the White Sox via Toronto on July 27. He is 3-0 in seven starts at Busch Stadium this season and 5-2 overall with the Cardinals. His workman-like approach to the game has made him a favorite among the fans.
The 28-year-old is an impending free agent and would like to stay in St. Louis. Yet he realizes that there might not be a spot for him in the starting rotation next season, assuming Adam Wainwright returns healthy.
"Definitely, I'm having fun," he said. "This is a place I wouldn't mind coming back to. But right now, my focus is on finishing out the season.
After the season, we'll see what happens."
Jackson, who resides in Atlanta, is 60-60 in his six-year career including a 30-30 mark at home and on the road. The 12 wins are his most since he won 13 in Detroit in 2009. His career high is 14 with Tampa Bay in 2008.
The much-traveled Jackson is with his seventh team. But no matter where he ends up next season, he says he will always remember his time in St. Louis.
"The fans are great," he said. "Even as a visitor coming in here, you could tell they were special. They make you feel good playing here."