The aim of the present work was to study seasonal and site-specific patterns of airborne fungal diversity, focusing on plant pathogens. The sampling of fungal spores was carried out for twelve months, i.e., between September 2017 and August 2018, using passive spore traps that were placed at three different sites in western (Lenkimai), central (Dubrava), and eastern (Labanoras) Lithuania. Samples were collected every 7–10 days, resulting in 146 samples altogether. Following DNA isolation, samples were individually amplified using ITS2 rRNA as a marker and subjected to high-throughput sequencing. Clustering and taxonomic classification of 283,006 high-quality reads showed the presence of 805 non-singleton fungal taxa. The detected fungi were 53.4% Ascomycota, 46.5% Basidiomycota, and 0.1% Mucoromycota. The most common fungal taxon at Labanoras and Lenkimai was Hannaella coprosmae (23.2% and 24.3% of all high-quality fungal sequences, respectively), while at Dubrava it was Cladosporium macrocarpum (16.0%). In different sites, plant pathogenic fungi constituted between 1.6% and 14.6% of all fungal taxa and among these the most common were Protomyces inouyei (4.6%) and Sydowia polyspora (1.9%). The results demonstrated that the diversity of airborne fungi was mainly determined by the surrounding vegetation and climatic factors, while the occurrence of pathogenic fungi was affected by the availability of their hosts.