The climate is strongly influenced by both the south-west and north-east monsoons. The south-west monsoons (April to October) bring extremely strong, hot and dry winds from Africa. There is little precipitation and extreme desiccation during these months. The north-east monsoons, not so strong as in the summer, begin in November and last until March.
Mean annual rainfall varies from about 150 mm on the costal plains to more than 1,000mm in the mountains. Rainfall is sporadic and there are some years when no rain falls. Nocturnal dew is far more important to the water supply than monsoonal rain, especially in the high altitude mountain belt. The mountainous cloud zone provides ground water and running water for the entire island. The dew and mist is channeled into small rooks and rivulets that support aquatic fauna and may flow the entire way from the mountains to the sea in winter.
The climate of Socotra is classified in the Köppen climate classification as BWh and BSh, meaning a tropical desert climate and semi-desert climate with a mean annual temperature over 18 °C (64 °F). Mean average tempertures range from 27º to 37ºC maximum and 17º to 26ºC minimum along the coastal plain. It is substantially cooler in the Haghier Mountains.
”Socotra Island xeric shrublands”. http://www.eoearth.org/article/Socotra_Island_xeric_shrublands