Madden-Julian Oscillation (MJO)

Outgoing longwave radiation (OLR) satellite data changes

NOAA source OLR data changed on 18 September, requiring technical updates to our processes. Until we implement these changes, NOAA images will be displayed for the MJO phase chart, the Latest OLR maps, and the Time longitude OLR chart. Regional cloudiness charts are temporarily unavailable.

The Madden-Julian Oscillation (MJO) is the major fluctuation in tropical weather on weekly to monthly timescales. The MJO can be characterised as an eastward moving 'pulse' of cloud and rainfall near the equator that typically recurs every 30 to 60 days.

MJO location and strength

These graphs show the strength and progression of the MJO through 8 different areas along the equator around the globe.
Area 3 is north west of Australia, 4 and 5 are to the north (the Maritime Continent), and 6 is to the north east.

RMM1 and RMM2 are mathematical methods that combine cloud amount and winds at upper and lower levels of the atmosphere to provide a measure of the strength and location of the MJO. When this index is within the centre circle the MJO is considered weak. Outside of this circle the index is stronger and will usually move in an anti-clockwise direction as the MJO moves from west to east.

Latest 40 day MJO phase chart from NOAA

MJO phase diagram

*Note: There are missing satellite observations from 16/3/1978 to 31/12/1978.

Average weekly rainfall probabilities

These maps show average weekly rainfall probabilities for each of the 8 MJO phases. Green shades indicate higher than normal expected rainfall, while brown shades indicates lower than normal expected rainfall.

Select the 'Wind' checkbox to also show the expected 850 hPa (approximately 1.5 km above sea level) wind anomalies. The direction and length of the arrows indicate the direction and strength of the wind anomaly. The darker the arrow, the more reliable the information is.

The relationship of the MJO with global weather patterns changes with the season.
Read more: The Combined Influence of the Madden–Julian Oscillation and El Niño–Southern Oscillation on Australian Rainfall.

Latest total and anomaly outgoing longwave radiation (OLR) from NOAA

Global maps of outgoing longwave radiation (OLR)

Global maps of outgoing longwave radiation (OLR) highlight regions experiencing more or less cloudiness. The top panel is the total OLR in Watts per square metre (W/m²) and the bottom panel is the anomaly (current minus the 1979-1998 climate average), in W/m². In the bottom panel, negative values (blue shading) represent above normal cloudiness while positive values (brown shading) represent below normal cloudiness.

Time longitude plots

Time longitude plots of daily averaged OLR anomalies (left) and 850 hPa (approximately 1.5 km above sea level) westerly wind anomalies (right) are useful for indicating the movement of the MJO.

How to read the Time longitude plots

The vertical axis represents time with the most distant past on the top and becoming more recent as you move down the chart. The Horizontal axis represents longitude.

Eastward movement of a strong MJO event would be seen as a diagonal line of violet (downward from left to right) in the OLR diagram, and a corresponding diagonal line of purple in the wind diagram. These diagonal lines would most likely fall between 60°E and 150°E and they would be repeated nearly every 1 to 2 months.

Daily averaged OLR anomalies from NOAA

Westerly wind anomalies

El Niño and positive Indian Ocean Dipole underway

The Bureau has declared an El Niño and a positive Indian Ocean Dipole (IOD) are underway. 

Sea surface temperature (SST) patterns across the Pacific Ocean have been consistent with El Niño thresholds since at least mid-winter in the southern hemisphere, but the overlying atmosphere has been slower to respond. More recently, the atmosphere has shown clearer signs of responding to the warm SSTs over the central and eastern tropical Pacific. The broad-scale pressure pattern for the last 30 days has reflected an El Niño, with low pressure anomalies over the central and eastern Pacific and high-pressure anomalies over Australia. The 90-day Southern Oscillation Index (SOI) is −7.8, meeting criteria indicative of El Niño (sustained values below −7). Recent trade wind strength has been generally close to average, but was slightly weaker than average across the Pacific in August 2023 for the first time since January 2020. Overall, there are signs of coupling of the Pacific Ocean and atmosphere. This coupling is a characteristic of an El Niño event and is what strengthens and sustains an event for an extended period. El Niño typically leads to reduced spring rainfall for eastern Australia. 

A positive IOD has also developed, with the Dipole Mode Index (DMI), also known as the IOD index, being above the positive IOD threshold (+0.4 °C) for the last five weeks. The IOD index for week ending 17 September was +1.25 °C. The longevity of this trend, combined with the strength of the dipole being observed and forecast, indicate a positive IOD event is underway. Cooler than average SSTs have been developing off the south-west coast of Indonesia since late August, while SSTs in the western Indian Ocean have remained warmer than average. 

All models indicate that El Niño will be sustained to at least until the end of summer while the positive IOD will be sustained to at least the end of spring. A combined El Niño and positive IOD can have significant impacts on northern Australian weather early on in the northern wet season (October to April). Some of the main outcomes that have historically been observed are lower than average rainfall from October to December, a later monsoon onset and low tropical cyclone activity at the start of the tropical cyclone season (November to April). Concurrent El Niño and positive IOD events can potentially lead to these impacts being exacerbated and extended further into the wet season. 

Recent concurrent events were in 2015, when a strong El Niño coincided with a positive IOD during spring of that year, and prior to that, 2006. Spring 2015 was 8th-warmest on record (since 1910) for northern Australia, with rainfall around 27% below the long-term (1961–1990) average.

Madden–Julian Oscillation weak

A weak pulse of the MJO is currently over the Maritime Continent. Climate models surveyed by the Bureau indicate the MJO will weaken as it continues to move over the Maritime Continent in the coming week.

Product code: IDCKGEW000

ACKNOWLEDGEMENT: Interpolated OLR data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA.

Product Code: IDCKGEM000