The physical health of 60 million people in developing countries is at risk due to the current El NiAo phenomenon.
That's according to the World Health Organization (WHO), which says the weather event is being associated with cholera, malaria, measles and other diseases in Africa, South America and the Pacific.
The UN agency has launched a report outlining health consequences and what steps can be taken to limit impacts.
Dianne Penn reports.
El NiAo has caused changing weather patterns across the planet, affecting rainfall and temperature, particularly in tropical regions.
For example, it has led to heavy rains and flooding in eastern Africa and extreme drought and water shortages in the Pacific.
That has spurred cholera in Tanzania, and increased malnutrition and diarrhoeal diseases in some south-western Pacific countries.
Dr Rick Brennan is Director of Emergency Risk Management and Humanitarian Response at the World Health Organization (WHO).
"So we have a broad range of potential impacts: from malnutrition, to infectious diseases, to disruptions of health services. And again, it's the most vulnerable: it's the poorest countries, it's the elderly, it's the children that are most impacted."
WHO has so far received requests for financial support totalling US $76 million from seven high-risk countries: Ethiopia, Lesotho, Kenya, Papua New Guinea, Somalia, Tanzania and Uganda.
The UN agency expects that more countries will follow suit as they work to provide additional health services, such as increased surveillance and emergency vaccination.
Dianne Penn, United Nations.
Source: United Nations.