The seasonality of phlebotomine sand flies was studied in Florida, utilizing colored light-emitting diode- and attractant-baited Mosquito Magnet MM-X traps from September 2006 to September 2008 at San Felasco Hammock Preserve State Park, Gainesville, FL. A total of 6,278 sand flies were collected from 314 actual nights and 1,692 total trap-nights, yielding 3.7 sand flies per trap-night. Lutzomyia shannoni was the predominant species, constituting 55% to 80% of the total sand fly populations collected during the studies. Both L. shannoni and L. vexator populations were highly seasonal and were moderately influenced by weather factors. Lutzomyia shannoni populations peaked in May and showed reduced activity during December, January, and February. This species was active throughout the year and showed positive and negative correlations with average monthly temperature and relative humidity, respectively. Lutzomyia vexator showed peak activity during August and October with an activity lull from December to March. This species showed a positive correlation with average monthly temperature. No correlations were observed with either species for average daily, weekly, or 1- to 8-wk-lagging precipitation, number of rainy days, wind speed, or lunar phases. Lutzomyia shannoni abundance was weakly correlated to L. vexator abundance. No other Lutzomyia spp. were collected during the study.