As mentioned, this was right on the Gulf of Mexico where it was both very hot in the day and very humid all the time.
In the early summer, the temperature dropped from the upper 90's in the day to the low 70s at night. In the worst of the summer, the temperatures were only dropping to the 80's, and they did use the air conditioners then.
However, that fan moved so much air that there would be a stiff wind blowing across the beds all night, and that cool humid wind would have you under the blankets in no time.
Fans like this aren't nearly as effective if either of these conditions is not met — then you're just pulling in air that is somewhat less uncomfortable each night, instead of getting truly refreshed.