Three subgroups within the Gilberts can be distinguished on the basis of rainfall: (i) north (Makin and Butaritari); (ii) center (from Marakei to Aranuka); and (iii) south (from Nonouti to Arorae) (Catala,1957).
Most of the Gilbert Islands and several of the Line and Phoenix Islands are located in the dry belt of the equatorial oceanic climatic zone. Islands located within 5° of the equator normally experience two wet seasons as the Intertropical Convergence Zone (ITCZ) crosses the region twice a year (Sturman and McGowan, 1999). However, rainfall is extremely variable, both annually and between islands being strongly influenced by El Nino Southern Oscillation (ENSO) events. Precipitation ranges from about 3,000 mm in the north (Butaritari) to 1,110 mm in the south (Tamana) in the Gilbert Group and from about 4,000 mm (Teraina) in the Line Islands to less than 800 mm in Kanton (Phoenix Group) (Burgess, 1987; Hoare, 1996-98). Prolonged droughts are common, notably in the central and southern Gilberts, many of the Phoenix Islands, and Kiritimati.
Hurricanes are rare.
Temperatures show little seasonal differences. Daytime maxima are high, averaging between 3 1° and 33° C., although humidity is more variable among the various islands.
Soil temperature regimes are isohyperthermic (> 22°C and <5°C between winter and summer)
Soil moisture regimes are generally ustic in the absence of ground water influences.
