Catalyzes the formation of flavonols from dihydroflavonols. It can act on dihydrokaempferol to produce kaempferol, on dihydroquercetin to produce quercitin and on dihydromyricetin to produce myricetin. 2-oxoglutarate + a (2R,3R)-dihydroflavonol + O2 = a flavonol + CO2 + H2O + succinate 2-oxoglutarate + a (2S)-flavan-4-one + O2 = a (2R,3R)-dihydroflavonol + CO2 + succinate Binds 1 ascorbate molecule per subunit. Binds 1 Fe cation per subunit. Secondary metabolite biosynthesis; flavonoid biosynthesis. Belongs to the iron/ascorbate-dependent oxidoreductase family.