From June to November, Galapagos weather is overcast and cool. The water around the islands is somewhat cold and the meeting of the Humboldt current and the warm air sometimes causes mist over the islands. Occasionally the Humboldt current is replaced by the warm El Niño current resulting in El Nino weather conditions: a phenomenon which occurs every few years can affect Galapagos weather conditions and throughout the South Pacific. From May to December, when the winds blow in a southeasterly direction, the shores of the southern islands are bathed in cool waters, chilling the air and creating unusually cold conditions for equatorial islands. During this period, rain is scarce on the coastal regions. Only plants that can survive long periods of time without water, such as lichens and cacti, thrive in these areas. Higher up, however, clouds of moisture support the thick vegetation.