Practice for the final round of the Shannons Nationals at Sydney Motorsport Park saw a lengthy delay as a thunderstorm lashed the Western Sydney venue.
Track running was delayed for almost 90 minutes after the storm hit at around 1400 local time.
Heavy rain, thunder, lightning and hail all added to the drama as competitors sat waiting for the day's action to resume.
A rejigged program eventually saw all sessions take place, albeit with shortened durations.
The morning's dry running naturally set all the quickest times, including Liam McAdam's 1:33.7s effort to edge Kumho V8 title rival Alex Rullo by 0.1s.
Dylan Thomas/Stuart Kostera (AMChamps), Ryan Simpson (GT3 Cup Challenge), Kim Burke (Radical Cup), Jack Perkins (Sports Sedans) and Mark Laucke (Sports Racers) set the pace in their respective classes.