Maximum sustained winds were close to hurricane force at 70 mph, the center said.
The Mexican government has issued a hurricane warning for the east coast of the Yucatán Peninsula from north of Punta Allen to Cancun, including Cozumel, the center said.
Gamma gained strength on Saturday morning when it was moving at a speed of 80 km / h.
A hurricane warning means that hurricane conditions are expected somewhere within the warning range, in this case within the next six hours. Preparations to protect life and property should be complete, says the Hurricane Center.
Gamma is expected to bring extremely heavy rain to parts of Mexico in the next few days. Flash floods and mudslides remain a concern as Gamma lands over Yucatán on Saturday.
On the current forecast route, the center of Gamma will move inland across the eastern Yucatan peninsula later on Saturday and continue via Yucatan until Sunday.
Gamma was not expected to affect the United States in the next week.
Gamma is not expected to become a major hurricane.