Nemanja Nikolic scores, Fire beat Dynamo 1-0
Kickoff was delayed nearly 40 minutes because of lightning in the area.
Nicolás Gaitán played a long arcing entry to Nikolic, who redirected it into the net from point-blank range to give Chicago the lead in the third minute of first-half stoppage time.
Kronholm finished with four saves. The 33-year-old, who spent the last 14 years playing professionally at various levels in Germany, signed with the Fire on May 7 and had his first MLS shutout in a 0-0 tie with D.C. United on July 27.
The Dynamo (9-11-3) have lost five of their last six games
Chicago (6-10-9) snapped a five-game winless streak dating to a 5-1 win over Atlanta United 5-1 on July 3 and got its first road win this season in 12 tries.