A handful of Zika cases have been identified and health officials are deciding which area or areas to include in any updated travel guidance, the source said.
The prospect of the virus spreading to the tourism-dependent Miami Beach area is likely to alarm tourism officials.
People traveling from San Francisco to Florida have a new Zika warning to consider after five people, three of whom were not from the state, were infected with the disease by local mosquitoes.
"We're in the midst of mosquito season and expect more Zika infections in the days and months to come", CDC Director Dr. Tom Frieden said.
In the past year, pregnant women have been advised not to travel to countries in Latin America where the Zika virus and infection is prevalent.
But since last summer, when the hardest hit country Brazil first reported a Zika outbreak, scientists have discovered that the virus can also be sexually transmitted.
The five cases in Miami Beach involve two local residents and three tourists - hailing from New York, Texas and Taiwan - Florida Governor Rick Scott told a news conference.
A team of experts across several disciplines at CDPH is working closely with local public health departments, vector control agencies and the medical community to ensure that California is responding aggressively and appropriately to the emerging threat of Zika virus. But the virus only causes mild, flu-like symptoms in most people, making it hard to confirm local transmissions, the CDC said.
Officials continue to struggle with controlling mosquitos in the Wynwood area of Miami, Frieden said.More news: Olympics-Cheruiyot's 16-year-wait ends and she takes to the marathon
Zika virus is a mosquito-borne flavivirus that was first identified in Uganda in 1947 in monkeys through a network that monitored yellow fever.
"Right now, the number of eggs we are getting is very much reduced in the treated site", Cornel said.
The director of the U.S. Centers for Disease Control and Prevention says officials will not be able to spray the South Beach area to prevent Zika as they have in other areas because of high-rise buildings and strong winds.
Things are much worse in the USA territory of Puerto Rico, where federal health officials have declared a public health emergency because Zika is spreading so rapidly among residents there.
With the Zika zones growing - this time into Miami Beach - some fear we could soon have our own.
Zika, often spread by mosquitoes, can cause life-threatening birth defects. "I'm anxious about how to communicate better so that people who should be anxious about Zika take the right measures to protect themselves, and that's mainly pregnant women and their partners".
Earlier this year, the Defense Department ordered heightened monitoring for the aedes aegypti mosquito at military installations in 27 states and the District of Columbia in response to the Zika crisis. However, the department also is investigating over six other infections outside that area.
This Q & A will tell you what you need to know about Zika.
According to the Centers for Disease Control and Prevention, those traveling to Mexico or are now in Mexico should continue to practice enhanced precautions when it comes to mosquitos - such as wearing long clothing, applying bug spray often, and using condoms during sex.