The common view of Florida is that it's a retirement state which is quite accurate and obvious when visiting many parts of the state. My wife and I are among the those that retired to South Florida.
"In Season" is when the snowbirds, holiday vacationers and students on Spring Break all head to Florida. The population bulge lasts from mid December to mid April as people seek to get away from the cold and seek the warmth found throughout most of the state. This period is well-known for a lot of people on the roads, restaurants and beaches. Residents typically complain about this surge of people and long for April when things quiet down and the tourists head back north.
As a fairly new transplant I don't mind the additional people visiting and welcome them to enjoy themselves and spend money supporting the tourist industry that's so critical to the economy. The tourist industry is why Florida is a tax-friendly state for retirees, with no state income tax, no state taxes on Social Security benefits, pensions, IRAs, 401(k)s and other retirement income along with no inheritance tax or estate tax is a major appeal.
It's widely said that Florida is full of old people which is true for vast parts of the state which was very apparent to my wife after moving here when we were sitting at a red light. I noticed she was scanning the surrounding cars as she turned to me and said; "they're all old!" I think that, with a chuckle, I suggested she look in a mirror.