MJO

MJO Fortnightly Update

Issued: 31 Dec 2025

No significant Madden-Julian Oscillation (MJO) signal was present in the last week of December 2025. Most models predict the MJO signal to remain inactive during the forecast period (5 – 18 January).

 

ALL Western MC Central MC Southern MC Eastern MC Central MSA Philippines
icon

Figure 1: Upper-tercile rainfall frequency for MJO phases based on GPCP (reference period: 2001-2020).

For each MJO phase, the upper tercile frequency is computed as the ratio of days with values exceeding the upper tercile threshold to the total number of days in that phase.

N corresponds to the number of days for each MJO phase.
icon

Figure 2: Correlation heatmap between RMM amplitude and 20–90 days bandpass-filtered daily rainfall based on GPCP data (Reference period: 2001–2020); Only correlation significant at the 95% level is shown. 

MC = Maritime Continent; MSA = Mainland Southeast Asia.
The qualitative outlook is assessed for the region in general. For specific updates on the national scale, the relevant ASEAN National Meteorological and Hydrological Services should be consulted.