<p>This paper describes the results of a study on sea level high-frequency oscillations observed at Trieste, north Adriatic Sea. Two records were available, namely an hourly record from 1917 to 2023, suitable for studying the events with time scales greater than a few hours, and a 1-min record from 2001 to 2023, for studying higher frequency events. We focused on the most prominent events observed in the summer months, when there is little influence of storm surges. The events from the 1-min record were used to study the connections with the atmospheric forcing. The dominant synoptic atmospheric patterns affecting the north Adriatic during these events consist of a cyclonic circulation at the surface and in the mid-troposphere, and strong gradients of mean sea level pressure and temperature in the low troposphere. The main sea level oscillations appear to correspond to the seiches of the Gulf of Trieste. The events from the hourly record allowed the construction of a centennial time series of annual event frequencies, which is characterised by two short periods of relatively low frequency in the 1940s to the early 1950s, and in the 2000s, which interrupt longer periods of higher frequency. A possible connection with the Atlantic Multidecadal Oscillation (<i>AMO</i>) was found, according to which, on average, the atmospheric conditions seem less favourable for large high frequency sea level oscillations in the Gulf of Trieste during positive <i>AMO</i> phases, and vice versa.</p>