This work had experimentally investigated the stability characteristics of nucleate and film boiling modes of methanol flowing over a nonuniformly heated flat plate. An axial (discrete) heat flux versus surface temperature distribution at which nucleate and film boiling can coexist steadily is identified at atmospheric and subatmospheric presssures and three liquid crossflow rates. Below this distribution, nucleate boiling mode is more stable; while above which, film boiling is more stable. Effects of system pressure and liquid crossflow rate were reported. This work discussed the co-existing heat fluxes and suggested the existence of a unique rather than two transition boiling curves, to the latter that is generally accepted in the literature, on a conductively heated surface.