Several phytopathogenic Fusarium species occurring worldwide on cereals as causal agents of ‘head blight’ (scab) of small grain cereals and ‘ear rot’ of maize, are capable of accumulating, in infected kernels, several mycotoxins some of which of notable impact to human and animal health. Fusarium graminearum, F. culmorum, F. poae, F. avenaceum and Microdochium nivale predominantly cause Fusarium diseases of small-grain cereals. Maize is predominantly attacked by F. graminearum, F. moniliforme, F. proliferatum and F. subglutinans. The review is focused on the influence of climatic variables, particularly temperature, humidity and rainfall on growth, reproduction, survival, competitive ability, mycotoxicity and pathogenicity of Fusarium fungi commonly isolated from wheat, barley and maize. Številne fitopatogene glive rodu Fusarium, ki povzročajo plesnivost klasov žit in koruznih storžev, je sposobnih v okuženih zrnih akumulirati številne mikotoksine, med katerimi so nekateri škodljivi za zdravje ljudi in živali. Žita prvenstveno okužujejo vrste Fusarium graminearum, F. culmorum, F. poae, F. avenaceum in Microdochium nivale, medtem ko koruzo F. graminearum, F. moniliforme, F. proliferatum in F. subglutinans. V pregledu je poudarek na vplivu vremenskih dejavnikov (temperatura, vlaga in padavine) na rast, razmnoževanje, preživetje, tekmovalno sposobnost, mikotoksičnost in patogenost Fusarium vrst, običajno izoliranih iz pšenice, ječmena in koruze.