Severe weather in other parts of the country is slowing vaccine shipments, causing another pause in Bay Area vaccine distribution.
A letter sent to Marin County residents who had appointments set for Thursday and Friday read: "Severe weather throughout the country has delayed our vaccine shipments."
People who had appointments for their second dose are encouraged to contact the county.
In Sonoma County, a shipment of more than 8,000 doses was delayed by the winter storms. They were to arrive earlier this week but still hadn't as of Wednesday.
At a press conference, county leaders said they have enough to keep vaccinations going for now.
The federal government has warned of widespread delays over the next few days.
State health leaders are suggesting that counties prioritize second doses over first doses for the next week if need be.