This year, one of the strongest El Niño events on record affected weather patterns worldwide, bringing with it major flooding and severe drought that impacted the health of millions. El Niño has ended, but scientists are now monitoring for the onset of its counterpart, La Niña, which may create conditions that exacerbate the spread of mosquito-borne diseases like Zika virus.

La Niña is characterized by the cooling of ocean surface waters in the equatorial Pacific and affects many of the same regions as El Niño. Based on previous years, this means above-average rainfall and potential flooding in southern Africa, Southeast Asia, and northern South America, and drier than average conditions in eastern Africa and the west coast of