Practically nowhere in California has been exempt from the rising number of COVID-19 cases around the state, which could mean the most extensive backward movement yet in its tiered reopening system Tuesday afternoon.

On Monday, counties around the state reported their highest total of coronavirus cases in a single day since late August — 7,761, according to data compiled by this news organization — and the seven-day average also rose to its highest point, now about 5,880 per day, since the same time, Aug. 25.

Monday afternoon, Gov. Gavin Newsom hinted at the possible bad news looming for some counties Tuesday.

“You’re starting to see an R-effective rate growing. You’re starting to see case rates growing. So I anticipate … that we’ll see some counties moving backward and not forward,” Newsom said, specifically noting Mono, Kings, Alpine and Shasta counties. “This is exactly why we designed the tier status the way we did. It was about being more and less restrictive, not based on political whim but based on the data.”

Despite the locales Newsom singled out, rising transmission hasn’t been contained just to the rural areas of the state.

The Bay Area, which has been largely inoculated from the worst of the virus, reported its third-highest single-day total of the entire pandemic — 1,411 cases reported around the region on Monday alone, a total it would have taken three or four days to reach for much of October.

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While the average number of cases reported in all of California has swelled by 33% in the past two weeks, in the Bay Area, it has soared by nearly double that rate — a 61% increase.

The total cases Monday were the most in the region since Aug. 14, while the daily average rose to its highest level — about 850 cases per day in the past week — since Sept. 4, according to data compiled by this news organization.

On Monday, Napa and Santa Cruz counties each recorded a record number of new cases, 118 and 148, respectively (each represents three days of test results because neither issues updates over the weekend). Six other counties in the region reported at least 100 new cases Monday, and every county in the region is reporting more cases now than it was two weeks ago.

In San Francisco, the daily average has increased by more than twofold, from about 36 cases per day two weeks ago to about 82 per day Monday. In Solano County, there are about double the number of new cases now than two weeks ago, while that figure has nearly tripled in Napa and Santa Cruz counties after single-day reporting records Monday.

The region-wide spike in cases means there is no county in the Bay Area with a per-capita case rate below 7.0/100K in the past week, according to this news organization’s tracking. That is the threshold for the purple, most-restrictive tier in the state’s reopening guidelines; however, it doesn’t mean the entire region is immediately moving backward.

First, the state uses a seven-day lag to account for any incomplete data. A county also has to show sustained regression, meaning it would have to fail to meet the mark for two straight weeks. There are also adjustments for testing and health equity, both of which many Bay Area jurisdictions have benefitted from.

Although the increase in cases has been disproportionately in the Bay Area, it has still been felt statewide.

In Los Angeles County, there has been about an uptick in cases of about 16%. Similarly in its inland neighbors, Riverside and San Bernardino counties, there are more new cases now than two weeks ago — but only by about 10%.

In the San Joaquin Valley, which was hit hard this summer, cases are on the rise, too — up about 48% from two weeks ago, but about one-quarter of what they were during a peak in mid-August.

As a region, the Bay Area’s per-capita infection rate remains lower than its counterparts elsewhere in California.

Altogether, the Bay Area reported about 74.2 new cases per 100,000 residents in the past week, compared to rates of about 130.2 in Los Angeles County, 134.1 in the Inland Empire, 101.7 on the Central Coast, 98.7 in the San Joaquin Valley, and 83.5 in Orange and San Diego counties, according to data compiled by this news organization.

And while Newsom noted California is testing at higher rates than any other point of the pandemic — more than 140,000 per day statewide — the Bay Area’s 12.9% increase in tests in the past two weeks isn’t enough to explain a 61% increase in new cases.

Statewide, the percentage of tests to come back positive has increased by nine-tenths of a point in the past week, to 4.1%, the highest seven-day positivity rate since the first week of September.

While California hasn’t been swarmed by the third wave sweeping across the Midwest — in North Dakota, hospitals reached 100% capacity and the governor authorized nurses diagnosed with COVID-19 to continue working — state and local health officials have warned of a potential second-coming of this summer’s surge in cases and hospitalizations.

Tuesday afternoon, Dr. Mark Ghaly, the Secretary of Health and Human Services, will announce exactly how many counties will be forced to abandon their reopening plans in the hopes of suppressing a similar surge.