Tonga
Narrative updated. “A powerhouse El Niño is brewing for 2026-27 — and Tonga is already being told to prepare”
Tonga is being urged to prepare as a strengthening El Niño approaches, with forecasters describing a powerhouse event brewing for 2026-27. Reanalysis for 9 July–6 October 2026 shows rainfall 36% below the 1991–2020 normal and mean temperatures 0.9°C below normal, though that window is Tonga's climatological dry season, so the real concern is a delayed onset of the November–April rains. Editorial coverage linking El Niño to the Hunga Tonga-Hunga Ha'apai eruption context underscores how compounding hazards shape the kingdom's exposure.
144.7 mm vs 225 mm normal
Reanalysis shows rainfall 36% below the 1991–2020 normal for 9 July–6 October 2026, though this window falls in Tonga's climatological dry season when totals are normally under 20 mm, so the more meaningful signal is the expected delay to the onset of the November–April rains.
News source22.29°C mean vs 23.24°C normal
Mean temperature for the same window ran 0.9°C below normal, a local cool anomaly that sits against the record-high global temperatures reported for 2025 and the strengthening El Niño signal.
News sourceEl Niño typically makes Tonga drier. Observed rainfall is running -36% — in line with the canonical response.
NASA POWER (MERRA-2) reanalysis, 9 Jul 2026 – 6 Oct 2026, sampled at the country centroid (-20.0°, -175.0°). Normals are 1991–2020. How this is computed
When it matters
Agricultural calendar for Tonga and where the El Niño impact window falls
Last 12 months vs normal
Observed monthly rainfall against the 1991–2020 climatology
Sector by sector
Rain-fed root crops and squash are likely to face delayed planting and below-normal rainfall through the November–March peak impact window.
Household rainwater tanks and island freshwater lenses are expected to come under strain if the wet season onset is delayed.
Drier conditions are expected to increase waterborne and vector-borne disease risk and threaten nutrition as local food production declines.
Reduced rainfall may lower hydropower and diesel-dependent supply reliability, raising generation costs on outer islands.
Warmer-than-normal ocean conditions during a strong El Niño typically shift tuna and coastal fish distribution, disrupting nearshore catches.
What happened last time
Past El Niño episodes and how Tonga responded. See the full ENSO timeline →
2023-24
A strong El Niño contributed to below-normal rainfall and drought declarations in parts of the Pacific, with Tonga monitoring water security through the wet season.
unsourced background2015-16
A powerful El Niño produced significant rainfall deficits across Tonga, prompting water rationing and agricultural losses during the November–March peak impact period.
unsourced background1997-98
One of the strongest El Niño events on record brought severe drought to Tonga and the wider southwest Pacific, with widespread crop failure and emergency water deliveries.
unsourced backgroundLatest coverage
RSSGlobal Temperature Report for 2025
Analysis: What are the causes of recent record-high global temperatures?
Editorial; El Niño and Hunga Tonga-Hunga Ha’apai
Tonga Told to Prepare as Powerhouse El Niño Brews for 2026-27
Tonga is being urged to prepare as a strengthening El Niño approaches, with forecasters describing a powerhouse event brewing for 2026-27. Reanalysis for 9 July–6 October 2026 shows rainfall 36% below
Nearby
Other countries in Polynesia