<p>A strong relationship between ENSO and rainfall in the main rain season (Oct-Jan) on the leeward islands of Aruba, Cura&ccedil;ao and Bonaire is found. It can easily be used for skillful seasonal predictions, with an anomaly correlation coefficient r~0.6 on historical data. The other two seasons, Feb-May and Jun-Sep, also show correlations with ENSO that can be exploited for predictions, r=0.4 to 0.5. Correlations with sea surface temperatures in other Pacific and Atlantic Ocean regions are present during the last 50 years, but are absent in earlier data. Most of these results are also applicable to other stations in northern South America. Regressions with the circulation show that the main intermediate factors are upper-level divergence and vorticity, and at lower levels a veering of the trade winds. This modifies the descending limb of the sea-continent breeze circulation that is responsible for the dry zone off the coast.</p>