Strong Relationship Between Betio precipitation on Tarawa Atoll (Kiribati) and Niño 3 SST Anomalies: Evidence from 1949 to 2025 Observations

Abstract Although the influence of the El Niño–Southern Oscillation (ENSO) on central Pacific rainfall is well recognized, quantitative assessments of contemporaneous and lagged relationships using official multi-decadal station observations remain scarce. We analyze monthly precipitation at Betio on Tarawa atoll for 1949–2025 provided by the Kiribati Meteorological Service, in relation to Niño 3 sea surface temperature (SST) anomalies. When the year is defined from May to April to include the boreal-winter peak of ENSO, annual precipitation at Betio is strongly related to the Niño 3 SST anomaly ( r = 0.83). Monthly precipitation is moderately related to the concurrent Niño 3 SST anomaly ( r = 0.55). Lag correlations remain statistically significant when Niño 3 SST leads rainfall by up to about 7 months, after the effective sample size is reduced to account for serial correlation. These results quantify the ENSO–rainfall linkage at Betio and indicate a practical lead time for drought early warning on a low-lying atoll.