To explore how seasonal climate patterns may influence the epidemiology of human keratomycosis.Retrospective ecological study.The seasonality of 52 episodes of dematiaceous fungal keratitis occurring along the Gulf of Mexico from 1972 to 2004 was examined. The temperature and relative humidity on the date of onset of 36 eyes with Curvularia keratitis was then compared with regional atmospheric conditions.A relative increase in the diagnosis of dematiaceous fungal keratitis occurred during late summer and persisted throughout autumn. The onset of Curvularia keratitis clustered in warm, humid months.Ocular phaeohyphomycosis, including curvulariosis, varies with seasonal weather in the subtropics.