Massive waves, coastal flooding and dangerous rip currents are roiling the California coastline this week as authorities advise people to take precautions while visiting beaches following two deaths last week.

Turbulent waters swept a five-year-old girl, who was walking with her mother and brother, out to sea from the shore of Treasure Island Beach in Orange county in southern California on Tuesday. Bystanders were able to rescue the mother and son, but the girl was not found and her body was recovered on Thursday.

In the city of Santa Cruz, the tide took two women to sea, leaving one dead and another in critical condition.

Meanwhile, in San Francisco sea water poured into the Embarcadero on Saturday night. The city saw its highest summer water level on record, according to the San Francisco Bay Area office of the National Weather Service.

The treacherous conditions were expected to last into this week with the continuing king tides, a non-scientific term describing the highest tides of the year.

Forecasts indicated southern California beaches would see dangerous rip currents and breaking waves and high tides, through at least late Wednesday. There is an elevated drowning risk as the conditions could pull people into the water, wash people off beaches and rocks, and capsize small boats, according to the National Weather Service.

“Remain out of the water due to hazardous swimming conditions, or stay near occupied lifeguard towers. Rock jetties can be deadly in such conditions, stay off the rocks,” the Los Angeles office of the NWS said in a Sunday evening message. Minor flooding would also be possible, the office said.

NWS officials in San Francisco warned of an increased risk of flooding of roads, lots and parks as well as sneaker waves, large breaking waves and strong rip currents, through Thursday morning. The office also advised residents to stay out of the water and warned travel may take longer.

In Orange county’s Newport Beach, city officials said the high tides could cause “flooding in low-lying harborfront neighborhoods”. Last week, the city manager’s office told residents to “take precautions, including installing seawall plugs and placing sandbags in vulnerable areas”.

During last week’s intense conditions, surfers rode massive waves at the Wedge in Newport Beach, which saw swells as high as 20ft. But the conditions have been challenging for surfers too, with several reporting highly dangerous and even near death experiences in the water.