The Campi Flegrei caldera, located west of Naples, is affected by slow vertical ground deformation, with maximum uplift centered in the Rione Terra area of Pozzuoli. Since 1905, six major uplift phases have been recorded, suggesting some degree of periodicity in the deformation process. However, this periodicity is irregular, owing to pronounced variations in the rate, duration, and associated seismicity of individual episodes.The mid-points of subsidence phases exhibit a relatively regular frequency; however, the existence of a true cyclicity in the bradyseismic phenomenon cannot be confirmed. This is due both to the anomaly represented by the 1982—1984 interval, which occurred at least three years out of phase with respect to the expected trend, and to the complete incongruence of the 2009—2021 interval, characterized by slow ground uplift during a period in which, by recurrence, subsidence would have been expected.Excluding these major and prolonged discrepancies, as well as shorter ones—likely attributable, at least up to the post-war period, to insufficient measurement frequency—a correlation can be observed between bradyseism and the lunar transit altitude in the local celestial sphere: Periods with lunar culminations <75° → Subsidence Periods with lunar culminations ≥75° → Uplift The analysis, which also aimed to interpret the discrepancies observed in the two main correlations, was conducted using three distinct approaches, sharing the use of lunar orbital parameters and high geometric accuracy. This accuracy was obtained by segmenting the lunar distance into five intervals and applying different levels of angular precision. Overall, the study reveals significant temporal coincidences between specific geometric configurations of the three main external gravitational sources acting on the Earth system and major geophysical phenomena recorded in the Campi Flegrei—Vesuvio volcanic area. These include: (i) the multi-year phases of vertical deformation, both periodic and aperiodic; (ii) the main inconsistencies with respect to such phases, (iii) the historical eruptive events (AD 79, 1302, 1538), (iv) the seismic crises of 1982—1984 and 2022—2025, (v) the short uplift episodes of 1976, 1989, 2000, 2005, and 2012, (vi) the major earthquake of 1883, seismic shocks of uncertain correlation in AD 37 and 1199, and some of the aforementioned events, such as those of 1302, 1976, and 2025.