Mengapa Banjir Tetap Mengepung Saat La Niña Melemah? Memahami "Fase Normal" yang Menipu

Early 2026 has proven to be a grueling test for Jakarta and much of Indonesia.

Although BMKG (the Meteorology, Climatology, and Geophysics Agency) predicts La Niña will weaken and transition into a Neutral phase by March 2026, rainfall is currently hitting its peak. Floods are surging, and the overcast skies show no signs of clearing.

Public confusion is growing: "If La Niña is weakening, shouldn't the rain be letting up?" The reality is far more complex. Here is the breakdown of the atmospheric forces at play.

1. What Exactly is a Neutral Phase?

A "Neutral phase" does not equate to "no rain." Within the ENSO (El Niño-Southern Oscillation) cycle, a neutral state occurs when surface temperatures in the Pacific Ocean hover around long-term averages. However, for an equatorial archipelago like Indonesia, "normal" conditions naturally involve high precipitation largely because the sea temperatures surrounding our islands remain exceptionally warm.

2. Why is the Rainfall So Extreme Right Now?

We are currently facing a "perfect storm" of overlapping climatic drivers:

• The Peak of the Asian Monsoon: From January to March, the Asian Monsoon winds carry vast amounts of moisture across Indonesia. This is an annual seasonal constant that remains powerful regardless of La Niña’s strength.
• Madden-Julian Oscillation (MJO): Currently, the MJO—an eastward-moving pulse of cloud and rainfall—is active over Indonesia. This wave triggers massive, large-scale cloud formation on a weekly basis.
• Cold Surges: Influxes of cold air from mainland Asia are pushing into Indonesian territory. These surges act as a catalyst, intensifying wind speeds and triggering extreme downpours across Western Indonesia, including the capital.

3. The Jakarta Impact: A Multi-Layered Crisis

In Jakarta, the problem is compounded by more than just local rainfall; it is a battle on three fronts:

• Local Intensity: Rainfall exceeding 100mm per day pushes the city’s drainage capacity to its absolute limit.
• Runoff from Upstream: Heavy rain in the highlands continues to send "sent floods" (water surges) down into the city’s river systems.
• Coastal Flooding (Rob): Lunar cycles are currently triggering high tides. This creates a "backwater" effect where river water cannot flow into the sea, causing prolonged inundation in Northern Jakarta.

4. Looking Toward March 2026: Staying Vigilant

BMKG warns that the transition phase—as La Niña shifts to Neutral—is often characterized by erratic and violent weather, including tornadoes, hailstorms, and short-duration "cloudbursts" that can be lethal.

A "Normal" forecast is not a signal to relax. On the contrary, clearing drainage systems, pruning aging trees, and ensuring pumping stations are fully operational in flood-prone zones must remain a top priority.