As New Zealand braces for an El Nino conditions, many parts of the Pacific are already facing their devastating effects.

Cyclone Tuni has passed over Samoa, American Samoa, Tonga and Niue in recent days.

Dry conditions have also created water shortages in Vanuatu, which is still recovering from Cyclone Pam earlier this year.

The severe tropical cyclone hit the country in March, destroying homes and ripping out crops.

World Vision's Dominica Leonard recently visited Vanuatu, where she met a woman who was eight months pregnant.

"She's cut down to one meal a day and one glass of water a day due to food shortages."

She said the country isn't used to food and water shortages.

"They're not used to going hungry and so they don't have the local knowledge of preserving food or knowing how to make things last."

El Nino is expected to make this summer's droughts and storms more severe, making it hard for residents to re-grow crops.

Dry conditions have also caused water shortages and malnutrition in Papua New Guinea.