In the Indo-Pacific Ocean (IPO), extreme significant wave heights (SWHs) can substantially induce coastal erosion, flooding, and devastating impacts on coastal livelihoods. This study examines the seasonal influence of the El Niño–Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), Southern Annular Mode (SAM), and Pacific North American (PNA) pattern on extreme wind-wave parameters. The climatic extremes are calculated utilizing ERA5 reanalysis datasets from 1979–2019 and a non-stationary generalized extreme value distribution. Significant increases in extreme wind-sea (Hmax) and swell SWH (HmaxSw) response to ENSO occur over the northeast North Pacific (NP) during December–February (DJF) and western NP during June–August (JJA). The PNA influence exhibits a similar pattern to ENSO during DJF yet is inactive in JJA. Hmax and HmaxSw responses to the IOD during September–November (SON) include significant increases over the western Pacific, southern Indian Ocean (IO) and southwest tropical IO yet decreases over the central tropical IO. The HmaxSw response to the SAM is larger than that for Hmax over the southern IPO during DJF, which extends towards the eastern Pacific in March–May (MAM). Overall, extreme wind-sea and swell parameter responses are found to be associated with sea level pressure (SLP) and SLP gradients