This study examines the influence of ENSO on rainfall intensity over the three main island groups in Kiribati: the Gilbert, Pheonix and Line islands. The four chosen islands were selected for their varying locations; Tarawa and Beru in the Gilbert island group, Kanton in the Phoenix island group and Kiritimati in the Line island group. Of the two in the Gilbert group, Tarawa is located in the central region and Beru is located in the southern region.

Since Kiribati is spread across vast regions of ocean, the study is aimed at correlating the sea surface temperature with recorded rainfall at these stations. This is designed to show the influence of the El Niño Southern Oscillation (ENSO) on Kiribati during the wet and dry season. The variation of rainfall in the country is also taken into consideration by comparing rainfall data from Tarawa with Beru, Kanton and Kiritimati rainfall. ENSO records from the Bureau of Meteorology were also compared with rainfall at these stations to investigate the influence of El Niño and La Niña phases.

The outcomes of this study showed that ENSO phases strongly influence rainfall patterns across Kiribati. During El Niño phases, higher rainfall is recorded whereas during La Niña phases, lower rainfall is recorded. A strong positive correlation between the sea surface temperature, ENSO and rainfall is demonstrated. Since rainfall is the only source of recharge for groundwater resources in Kiribati, knowledge of the influence of ENSO events is essential to planning for the subsequent impacts.