Dissolved boron and sodium concentrations were determined in rainfall collected on the Gulf Coast of northern Florida in order to investigate chemical and physical processes influencing natural concentration levels in the coastal marine atmosphere. Rainfall samples were collected during summer showers, during drizzle and heavy downpours associated with winter frontal activities, and sequentially during tropical storm Becky. Mean calculated B enrichments E//N//a(B) for summer and winter sample sets were 32 and 11, respectively. A surprisingly constant concentration of 'excess' B above that expected from direct seawater injection of approximately 6 mu g 1** minus **1 was observed in the sequential Becky samples. The lower winter B/Na ratios, and thus the calculated E//N//a(B) values, appear related to higher Na concentrations; however, several alternative hypotheses can be advanced to explain the results, including greater particulate sea-salt injection during winter months, incorporation of soil materials with a B/Na ratio above the seawater value, and possible influences of temperature variation on gaseous B incorporation in rain and evaporation from the sea surface