Biodiversity indices are frequently used to provide a numerical value of the diversity of species within an ecological community. To study fungal biodiversity in the air, a 7-day recording Hirsttype spore trap was used. The daily concentration of 124 taxa was recorded in an Italian vineyard. The predominant fungi were: Cladosporium spp., unknown 3-septate fusiform spore, and Alternaria spp. Shannon's and Simpson's biodiversity indices and evenness were calculated first for air spora. Meteorological circumstances affected the biodiversity; positive correlations were found between Simpson's biodiversity index and precipitation, but no significant correlations were found with Shannon's diversity index and evenness. To predict Simpson's index for airborne fungi, regression analysis was performed. It was shown that the best estimator, sun hours, negatively affected the index. The biodiversity of the dominant species was low on dry days, since Cladosporium alone had much higher abundance on such days than other species.