Coronavirus infections and hospitalizations continued to climb in California and many parts of the Bay Area over the weekend, as the state that found early success in containing the virus is now scrambling to tamp down outbreaks in prisons and spiking new cases among young people.

Statewide, the average number of new cases per day doubled from just under 2,000 in May to 4,000 in June. That number jumped to a daily average of 6,700 new cases the first four days of July alone, according to Chronicle data.

“The damage that COVID-19 can do — this pandemic — is still in front of us,” Gov. Gavin Newsom said Monday. “It continues to spread at rates we have not experienced here in the state of California since the beginning of this pandemic.”

The number of people hospitalized with COVID-19 in California hit a record high, 5,690, for the 17th consecutive day. As of July 5, according to Chronicle data, the Bay Area had 494 patients hospitalized, down from its all-time high of 508 on July 3. Prior to the recent spike in cases, the Bay Area had reached a high of 471 hospitalizations on April 7.

The rate of positive tests has also climbed to 6.8% — up from 5.6% last week. It had been holding steady at 4.9% the previous several weeks, and its steady climb indicates the infection is spreading more quickly now than before.

Deaths, however, are declining statewide and in the Bay Area — from an average of 69 per day in May to 64 per day in June in California. The average number of deaths went from 4.8 to 4.5 in the Bay Area during the same period. That may be because more young people are getting diagnosed and hospitalized, but the severity of disease among younger patients is not as acute as it is in older patients, Newsom said.

People line up to buy fireworks from a stand in San Bruno on Friday, July 3, 2020.Photo: Nick Otto / Special to The Chronicle
In the Bay Area, the average number of new cases per day spiked 114%, from 182 in May to 390 in June, and 800 the first four days of July. The Bay Area reported a record-high 1,010 new cases Thursday — the first time the region has surpassed 1,000 new cases a day since the pandemic began.

As of Monday evening, there were 2.9 million confirmed cases in the United States, including 130,284 deaths. California reported 273,303 cases, including 6,450 deaths.

Much of the recent increase has come from large clusters of infections at prisons and nursing homes, as well as community transmission among members of the public as counties have reopened restaurants and businesses over the last several weeks.

Marin County on Sunday said it will suspend indoor dining for at least three weeks, after previously allowing it. Marin is one of 23 counties on a state watch list of counties that are showing warning signs of coronavirus spreading at concerning rates.

The outbreak at San Quentin State Prison in Marin County, where nearly 1,400 inmates have tested positive for the coronavirus, is putting new strain on hospitals that are admitting the patients — in particular at nearby Marin General, Newsom said. The prison is now also sending inmates to Saint Francis Memorial Hospital in San Francisco and Seton Medical Center in Daly City so those hospitals can help share the responsibility of caring for the patients, Newsom said.

The San Quentin outbreak accounts for more than half of the 2,445 cases that have emerged inside state prisons.

The state over the weekend rejected Santa Clara County’s application to move faster toward reopening. A July 2 county order that allows some activities to resume — including outdoor gatherings of up to 60 people and indoor gatherings of up to 20 people, with some restrictions — is scheduled to take effect on July 13 or when the county gets state approval, whichever date comes later.

Over the holiday weekend, state regulators visited nearly 6,000 bars and restaurants and issued just 52 citations for violations of coronavirus safety guidelines. Newsom said it was an encouraging sign that most Californians are doing the right thing as the state struggles to reopen amid a surging caseload.

After ordering bars and indoor dining closed in most of the state last week, Newsom said that agents with the Department of Alcohol Beverage Control stepped up their enforcement during the Fourth of July weekend out of concern that more people would be out celebrating and visited 5,986 businesses between Thursday and Sunday.

The governor said his administration sent enforcement teams to six key regions across the state with known violators or high-risk workplaces, though he did not specify where those were. He said the effort was more about educating business owners, and state regulators cited only those who were unwilling or unable to make changes to their operations.

“There were only a handful of citations because the overwhelming majority of people were doing the right thing,” Newsom said at a news conference. “I was very encouraged by the team that came back and said that even if people were out of compliance, the engagement got people back into compliance very quickly.”

California is trying to control a coronavirus outbreak that has taken a turn for the worse in recent weeks, following a loosening of restrictions on businesses and public life.

The state is closely monitoring 23 of California’s 58 counties, including Contra Costa, Marin and  Solano in the Bay Area, because of their high rate of new infections, positive tests or increasing hospitalizations. Of the 20 most populous counties in the state, all but five — Alameda, San Francisco, San Mateo, Santa Clara and Sonoma — are on the watch list. Napa County is also not being monitored.

Santa Clara County, which was previously flagged for an accelerating rise in hospitalizations, fell off the list over the weekend. After being removed late last week, Contra Costa County was added back.

Counties that have been on the list for three consecutive days must close bars and indoor dining, wineries, tasting rooms, family entertainment centers, movie theaters, museums, zoos and card rooms for at least three weeks.