Most of the island's ample supply of water is brought by the trade winds. Although amounts vary with the location, rain is possible throughout the year, with the greatest monthly totals recorded from June through October. Average yearly rainfall along the windward east coast frequently exceeds , and exposed mountainsides receive up to , among the highest accumulations in the Caribbean and the world. Totals on the leeward west coast, however, are only about per year. Humidities are closely tied to rainfall patterns, with the highest values occurring on windward slopes and the lowest in sheltered areas. Relative humidity readings between 70 percent and 90 percent have been recorded in Roseau.