There are some cases when a DUI charge in Florida is a felony. However, if this is your first-offense, then the DUI charge is almost always considered a misdemeanor.
In Florida, if you already have two DUI convictions within the past 10 years, you will be charged with felony DUI. If you get caught drinking and driving a fourth time or more, then you will be charged with felony DUI in Florida regardless of how recent your past convictions were.
Also, even if this is your first-offense, if your DUI involves serious property damage or injury to another individual, you could be charged with a very serious felony. Felony DUIs can result in much harsher penalties including years in prison and fines well into the thousands of dollars.