On March 20, 2015, Kempin was again sent on loan, this time joining North American Soccer League club San Antonio Scorpions for the duration of the 2015 season.
SKC manager Peter Vermes said that Kempin was headed to San Antonio, instead of affiliate club OKC Energy, because "[he] has the ability to go in and be the number one right away in San Antonio."
He started each of the Scorpions' first two matches on the year, conceding five total goals in defeats against Tampa Bay Rowdies on April 4 and Indy Eleven on April 18.

After Luis Marín terminated his contract with the club, Kempin was recalled to Sporting Kansas City on May 27, 2015.
He spent the majority of the season backing up Tim Melia, but did appear three times in a four-match stretch in August.
Kempin's only other appearance on the year came in the knockout round of the 2015 MLS Cup Playoffs, in a match that would become known as the "Double Post" game.
Against eventual champions Portland Timbers, Melia suffered a head injury and had to exit the match in the 84th minute.
Kempin did not concede a goal through extra time, and made three saves in the ensuing penalty shootout, but saw his kick in the 11th round saved as Portland advanced by a 7–6 scoreline.
Although his contract expired at the end of the season, Kempin re-signed with Sporting KC on December 9.
On March 20, 2015, Kempin was again sent on loan, this time joining North American Soccer League club San Antonio Scorpions for the duration of the 2015 season. SKC manager Peter Vermes said that Kempin was headed to San Antonio, instead of affiliate club OKC Energy, because "[he] has the ability to go in and be the number one right away in San Antonio." He started each of the Scorpions' first two matches on the year, conceding five total goals in defeats against Tampa Bay Rowdies on April 4 and Indy Eleven on April 18.
After Luis Marín terminated his contract with the club, Kempin was recalled to Sporting Kansas City on May 27, 2015. He spent the majority of the season backing up Tim Melia, but did appear three times in a four-match stretch in August. Kempin's only other appearance on the year came in the knockout round of the 2015 MLS Cup Playoffs, in a match that would become known as the "Double Post" game. Against eventual champions Portland Timbers, Melia suffered a head injury and had to exit the match in the 84th minute. Kempin did not concede a goal through extra time, and made three saves in the ensuing penalty shootout, but saw his kick in the 11th round saved as Portland advanced by a 7–6 scoreline. Although his contract expired at the end of the season, Kempin re-signed with Sporting KC on December 9.
Jon Kempin