Vanuatu is grappling with severe drought, one year on from the devastation of Cyclone Pam.
The category five cyclone pummelled the country in March last year, with winds gusting more than 320 km/h, destroying 90 percent of the country's food crops and leaving 75,000 people homeless.
Aid agency CARE Australia said decimation was the "only word for what happened in Vanuatu".
It said the country's crops had not recovered, and a drought driven by El Niño was now crippling the country.
"Here your food garden is your lifeline, so people in Vanuatu are now dealing with an overwhelming double crisis," CARE Vanuatu programme manager Charlie Damon said.
Meanwhile, UNICEF warned severe storms were becoming more frequent and more devastating.
It said the Pacific had always experienced natural disasters, but global warming and rising ocean temperatures were leading to more of them.
After Cyclone Winston hit the Pacific in February, UNICEF Pacific representative Karen Allen said it was unprecedented to have two category five cyclones occurring in the past year - with only 11 category five cyclones recorded south of the equator in the last 45 years.
Dr Allen said the implications were immense and the way buildings were constructed needed to be re-evaluated.
"We need to consider everything, from the way we build homes, schools, health facilities and other critical infrastructure such as water and power supply, to the way that families prepare themselves, their crops and their livelihoods."
Pacific countries needed to plan and prepare for all eventualities, including the prospect of a direct hit by a category five cyclone, she said.
"People are trying to figure that out, trying to understand the enormity of the resources that will be required.
"It's clear that the traditional coping mechanisms, and the traditional places that people ran to during a storm, even those, are not sufficient," Dr Allen said.