An April–May 2020 bloom of the red tide microalga Lingulodinium polyedra developed to an unprecedented size, extending from northern Baja California to the Santa Barbara Channel. The L. polyedra strain is native to coastal California and is known to produce low levels of a toxic di-sulfated polyether named yessotoxin (YTX). In order to assess the evolution of the YTX content throughout the bloom and its transfer to water and aerosols, the concentration of YTX analogs was measured in the particulate and the dissolved organic matter of the sea surface water as well as in onshore sea spray aerosols. The YTX cell content was characteristic of Californian strains of L. polyedra. A lower production of YTX analogs by the cells at the peak of the bloom was detected, yielding total YTX content (particulate + dissolved) ranging from below the detection limit to 6.89 ng L−1 at that time. Yessotoxin and homo-yessotoxin were detected in sea spray aerosol measured onshore (from below detection limit to 20.67 ± 8.37 pg m−3), constituting the first detection of YTX analogs in coastal aerosols. The aerosolized YTX did not correlate with the seawater content but rather with westerly winds and higher tides. The presence of YTX in aerosols motivates further investigation into potential correlations with adverse effects in humans.