Jewish emigration to the states can typically be generalized into three distinct waves during the 19th and 20th centuries.

The first was during the mid-19th century with a large influx of Jews from German speaking states and mixing in with settlements across the country. Communities typically formed where Jews from the same towns across the pond would live in roughly the same areas in the United States.

The second, the one to which you refer, spanned the end of the 19th century and the beginnings of the 20th century with a large emigration of Jews from communities in Eastern Europe and the Pale. This emigration, also when my family came in, was largely focused on New York City as an entry point. Zionism in the United States is largely rooted from this influx of immigrants. To my knowledge there is no record of Jews moving to the southern states during this time.

The third and final distinct emigration came long after WW2 with the refuseniks of the Soviet Union who were escaping ever restricting Soviet policies against Jews and their businesses. A mix of these immigrants, as well as ones from the second wave, started moving to Florida in the late 1940s and beyond.

There isn't much verifiable and documented reasoning as to why Florida. Florida isn't necessarily the only city that saw large influxes of Jewish life besides New York either. Most notable other communities are spread out in other places across New England as well as California. What can be said is that Florida was probably picked for the same reasons as many other Americans that moved down there. Better weather, they found a community, and the rest is history.