All countries

Southeast Asia

Indonesia

Warmer than average

Seasonal outlook

September to November 2026

Likely warmer than usual

The European seasonal forecast model expects Indonesia to average about 1.4°C warmer than usual for this time of year.

Cooler 21%About usual 21%Warmer 58%

Estimated chance of each outcome. With no forecast signal, each would be about 1 in 3.

High confidence
A strong signal. Outcomes usually follow it, but not always.
Source
European seasonal forecast (ECMWF), via Copernicus
Technical details
  • Model: ECMWF SEAS5 (system 51) ensemble mean, from the Copernicus Climate Data Store.
  • 2 m air temperature anomaly: +1.42°C, averaged over September to November 2026, relative to the model's 1993 to 2016 average.
  • Taken at the model grid point nearest -0.80, 113.90, so it represents that area rather than the whole country.
  • Chances (cooler / about usual / warmer): 21% / 21% / 58%. Estimated by Nino Tracker from the size of the anomaly, because the ensemble mean product does not include the model's own odds.
  • Confidence is set by the anomaly's size: under 0.5°C low, 0.5 to 1°C moderate, 1°C or more high.

El Niño right now

Strong El Niño

El Niño is a natural warming of the central and eastern tropical Pacific Ocean that shifts weather patterns around the world. Over June to August 2026, sea temperatures there averaged about 1.8°C above normal, which counts as a strong event.

Technical details
  • Oceanic Niño Index (ONI): +1.80 for JJA 2026. It is the 3-month average sea surface temperature anomaly in the Niño 3.4 region (5°N to 5°S, 120°W to 170°W), from NOAA.
  • El Niño conditions are +0.5°C or more, La Niña −0.5°C or less, sustained for five overlapping 3-month seasons. Strength: weak 0.5 to 0.9, moderate 1.0 to 1.4, strong 1.5 to 1.9, very strong 2.0 or more.
  • NOAA now uses a relative version of this index (RONI) for official monitoring. The ONI is still published each month.
  • Last updated Sep 23, 2026, 6:56 PM UTC.

Upcoming 7 Days

Jakarta
25–36°
Drizzle
28.9° avg
Last year
28.0° avg
0.9° cooler
Surabaya
26–32°
Partly cloudy
28.7° avg
Last year
30.1° avg
1.4° warmer
Medan
23–31°
Thunderstorms
26.2° avg
Last year
26.3° avg
About the same
Denpasar
22–30°
Drizzle
26.3° avg
Last year
26.0° avg
About the same
Last year this week · Sep 23 to 29, 2025

Across these 4 cities, it averaged 27.6°, about the same as this week's forecast of 27.5°.

Updated Sep 23, 2026, 6:56 PM UTC

Nino Tracker updates weather data two times a day.