A rise in positive Covid-19 cases in Marin this week can be attributed to Memorial Day weekend activity, an outbreak in the Canal area of San Rafael and increased testing, public health officials said. Marin now has over 600 cases and is seeing an average of 20 new cases a day, but the key metric, hospitalizations, is stable at two, so the relaxation of the shelter-in-place order continues. This week, outdoor demonstrations and faith-based ceremonies were allowed, and indoor retail will be allowed on Friday. Indoor dining, hair salons, gyms and overnight lodging will be allowed at the end of the month. Dr. Lisa Santora, Marin’s deputy public health officer, stressed that individuals must stay vigilant. “Over Memorial Day weekend, we saw residents break from shelter-in-place guidance. After months of feeling cooped up and disconnected, families went on road trips and neighbors gathered—sometimes wearing face covers, sometimes not. Sometimes staying six feet apart, sometimes not.” Dr. Santora said she also observed demonstrations this weekend where people from different households traveled in the same car without face coverings, so the health department is encouraging everyone who participated in a demonstration to get tested next week. (Visit lhi.care to schedule an appointment.) At the Board of Supervisors meeting on Tuesday, public health officer Dr. Matt Willis warned of a second surge in the late summer. Three new models of infection rates in California forecast a big increase in infections beginning in August, based on the anticipated weakening of protective measures like the shelter-in place order, hand washing and mask wearing. A lot of attention was given to modeling early in the epidemic, but the shelter-in-place order made those predictions too high. With the shelter order mostly lifted, Dr. Willis said modeling can be helpful again. He estimated that 5 percent of Marin has been infected, which means 95 percent remains susceptible. In West Marin, fewer than 10 people have tested positive. “The risk of that second surge is real,” Dr. Willis said.