Tuvalu experiences the effects of El Niño and La Niña, which is caused by changes in ocean temperatures in the equatorial and central Pacific. El Niño effects increase the chances of tropical storms and cyclones, while La Niña effects increase the chances of drought. Typically the islands of Tuvalu receive between  of rainfall per month. The central Pacific Ocean experiences changes from periods of La Niña to periods of El Niño.