The county reported 1,422 COVID-19 diagnoses, raising the cumulative case total to 71,116. But the county did not report any new fatalities, leaving the death toll at 1,554.
The latest diagnoses did not all happen since Sunday, but are spread out over several days. The largest previous case total this month came on Nov. 16, when 935 positive cases were recorded. The previous worst single-day total so far during the pandemic was on July 7, when 1,060 cases were recorded.
The number of county residents hospitalized with the coronavirus increased from 380 Sunday to 428 on Monday, with the number of patients in intensive care rising from 91 to 105, according to the Orange County Health Care Agency.
Travelers arriving in LA required to sign COVID-19 form acknowledging state quarantine
The change in the three-day average of hospitalized patients inched up from 24.6% to 26.4%. The county has 25% of its intensive care unit beds and 66% of its ventilators available.
The worst day for hospitalizations so far was July 14, when 722 people were hospitalized for COVID-19. The last time it was as high as it is now was in mid-August.
"It looks horrible," Orange County CEO Frank Kim said of the most recent statistics. "I was dreading seeing a large number like that.''
But it's a trend throughout Southern California, Kim noted.
"We saw San Bernardino County with numbers (of cases) in the two thousands,'' Kim said. "It's just really bad in Southern California. I just don't think people are taking it seriously enough. It's not a judgment. I don't know how you get people to take it more seriously."