The Cocos (Keeling) Islands are situated in the humid tropical zone and are at the southern edge of the equatorial low pressure belt which moves northwards and southwards according to the season. The Islands are subject to the north-west monsoons from January to May moderated by oceanic conditions. Relatively strong constant south-east trade winds blow for much of the year outside the monsoon season and often during it.
There is an annual rainfall varying between about 844 and 3,289 mm with an average of 1,976 mm pa and relatively uniform temperatures, with an average daily maximum temperature of 28.9°C and average daily minimum temperature of 24.4°C and relative humidity typically ranging between 65% and 90% with a mean of 75%. The predominant wind direction is east to southeast for all months, showing the influence of the southeast trade winds.
Information about the historical and forecasted rainfall, temperatures and relative humidity in the Cocos (Keeling) Islands region can be found at the Bureau of Meteorology's Cocos Island area page
Cyclones have the potential to have serious effects on the flora and fauna of the islands. Further information on cyclones can be obtained from the Bureau of Meteorology. One of the most damaging cyclones in recent times was 'Doreen', which passed directly over the South Keeling atoll in 1968. Cyclone 'John', in 1989 tracked close to the North Keeling Island and caused scattered pockets of damage to the vegetation. Cyclone 'Walter', in April 2001, passed close by North Keeling Island and wreaked considerable damage on the vegetation. 61% of the rainforest canopy fell to the ground, and 14% of the trees were completely felled. Large numbers of birds were killed. Park staff have commenced an intensive monitoring program to record post-cyclone recovery.