The county was on track to move up from the red tier to the less restrictive orange tier of the state's color-coded tracking system. But the region did not advance on Tuesday, remaining in the red tier.
MORE: Here are all the counties that can, cannot reopen under CA color-coded system
The next chance to advance to the next tier would be mid-October.
The case rate per 100,000 people is expected to be a little above 4, the ceiling for the orange tier, Orange County CEO Frank Kim said.
WATCH | 7 things we've learned about COVID-19 in the last 7 months
It's possible it was a "holiday spike" related to Labor Day as county officials still work to discourage get-togethers among friends and extended family, Kim said.
The small spike in cases per 100,000 people "doesn't signify something terrible in the community," Kim said.
RELATED: Here's a breakdown of each tier in California's new reopening framework
"When you get down to around 3.5 to 4 cases per 100,000 that's very small," Kim said.
Having trouble viewing? For a better experience, click here to open in a new window
Kim said it is difficult to track down the source of outbreaks given the small sample size. However, he did say young adults renting out vacation residencies is an issue.
Orange County Supervisor Lisa Bartlett said there is concern about a see-sawing back and forth between the red and orange tiers, because if the county has to step back a tier that locks it into place for at least three weeks even if the metrics match a less-restrictive tier.
City News Service contributed to this report.