The Wooley Grange round has been rescheduled for September 8/9.
Representatives from RHL Activities and Race Direction inspected the track on Friday morning and the decision to postpone the event was unanimous.
"It's a shame we've had to postpone this weekend's event, as we already had everything in place, but rider safety is paramount and the track is unsafe to race on because of the weather," explained Gareth Hockey, director of RHL Activities, which runs the series on behalf of the ACU.
"We waited until this morning before making the decision, on the off chance that conditions would improve.
"Despite the best efforts of the local club, RHL Activities and everyone involved in this weekend's event, more rain overnight basically turned the track into a swamp and, with more rain forecast, it isn't going to improve soon."
Entries for this weekend's event will automatically be carried over to the rescheduled round at Wooley Grange, which will take place over the weekend of September 8/9.
The Pontrillas round originally scheduled for that September weekend has been moved forwad and will now run over the weekend of July 14/15.