The disease, spread by infected mosquitoes, is at its worst during warm and humid climatic seasons.
The fever is already at epidemic levels in New Caledonia - with 127 cases of Type 1 dengue recorded last month and 34 cases so far in December.
The Federated States of Micronesia has had just under 500 cases of Type 4 reported, with no deaths, and about 150 people admitted to hospital.
The Cook Islands and Solomon Islands have also been alerted to possible infection.
Dr Yvan Souares, an epidemiologist with the Secretariat of the Pacific Community, based in New Caledonia, described the scale of the problem to Radio Australia's Pacific Beat.
Experts in his field study health and disease and seek methods of preventing outbreaks of illness.
Dr Soares said New Caledonia was just at the start of the latest outbreak, which had begun earlier than in any other year.
This could indicate a moderate to high-level epidemic. But certain factors, such as previously infected victims having immunity from prior exposure to a different type of dengue, might hold the outbreak at a moderate level.
The epidemic was being well monitored, with the Dengue National Committee beginning its annual monitoring in October. However, if it worsened, resources could become stretched and authorities were ordering more equipment and pesticide.
Dr Soares said the challenge for the community was to control the mosquito and this could be done by eliminating breeding sites, even down to emptying water from coconut shells, gutters and buckets.
The epidemiologist said Micronesia had about 500 cases, developing in the past couple of months, and 154 people admitted to hospital.
The Cook Islands had isolated one patient - who it discovered had been in Solomon Islands for the previous six months. Health authorities in the Solomons have been alerted and urged to begin community monitoring of possible mosquito breeding sites.
Dengue can bring not only fever but headache, sore muscles, nausea, vomiting and a rash.