SAN JOSE (KPIX 5) – Bay Area pot shops are getting ready to celebrate 4/20, but the state of California has issued a warning that could fine dispensaries if they break the rules.

When 4/20 rolls around on Friday, it will be the first since recreational marijuana became legal in California.

It means big business for dispensaries across the Bay Area, including Buddy’s in San Jose.

On Tuesday, the state issued a warning to licensed dispensaries ahead of the big celebration.

Buddy’s Cannabis says it usually gets 400 people through its doors a day. But this week, it’s seen up to 700 a day.

“We’re still in the early stages of transitioning from a black market to a legal market, and some folks still need to know what the rules are,” said Matt Lucero, the owner of Buddy’s Cannabis.

Buddy’s, which was the first to receive a state license to sell recreational marijuana, was notified via email.

The California Bureau of Cannabis Control sent a warning to legal dispensaries stating that they could face fines if they participate in unlicensed temporary events away from their stores.

The bureau has issued specific licenses to groups that are limited to holding marijuana celebrations on county fairgrounds.

“Obviously, the state is interested in tracking and tracing all sales of cannabis,” said Lucero. “So they don’t want to have these sort of free, open events where there’s a lot of sales that are going on without consideration for tax and inventory.”

Every year, San Francisco’s biggest unofficial cannabis celebration happens at Hippie Hill in Golden Gate Park.

It is a long-time tradition that attracts upwards of 15,000 party-goers.

“I’m going to smoke a lot of marijuana,” said San Jose resident Richard Cruz.

“I’ve been doing 4/20, celebrating it, for five, six years,” said San Jose resident Andrew Worley. “And it was nothing in San Jose like six years ago, to where it is now. It’s come a long way.”