Risk Management and El Niño and La Niña

ENSO episodes and patterns

El Niño-Southern Oscillation (ENSO) describes the cycle of El Niño, neutral and La Niña patterns in the Pacific Ocean, which occur on time scales of typically 3-7 years. El Niños often lead to drier conditions over large parts of Australia, while La Niñas tend to enhance rainfall over much of the continent.
Depending on the time of year, El Niño and La Niña can also affect the:

  • likelihood of frost;
  • likelihood of flood risk;
  • number of rain days;
  • likelihood of heat waves;
  • evaporation;
  • onset and cessation of the northern monsoon; and
  • movement, impact and frequency of the Madden Julian Oscillation.

Further information on El Niño and La Niña is available from the Bureau's Australian Climate Influences web page.

Changes in Australian conditions that result from shifting from one stage of the cycle to the next, or even a longer term continuation of one part of the cycle, (for instance, two La Niña events in a row), raise risks that may require significant changes in farm planning and decision making.

Agricultural decisions and ENSO episodes and patterns

Agricultural planning and decision making is often focused around the current crop or pasture growing season, as well as for periods out to one year. These timescales are exactly those impacted by the extremes of ENSO - La Niña and El Niño - both of which often last for about 10-12 months, and typically have biggest impact in the Australian winter and spring; key times agriculturally.

To manage the risk that El Niño and La Niña present, it is important to monitor the status of ENSO, and furthermore, to be aware that no two El Niño or La Niña episodes, or their impacts upon Australia, are identical.

Recommended actions include:

  • Monitoring the probabilities (chances) of an event occurring, for example, by regularly updating yourself with information from the Bureau's 'ENSO Wrap Up' web pages, which offer assessments of where we lie within the ENSO cycle.
  • During an event, keeping a regular watch on the Bureau's seasonal climate outlooks for information on the season (3-months) ahead for both rainfall and temperature, as it is during the extremes of ENSO that the outlooks typically have greatest skill.
  • Watching the Bureau's weather forecasts, such as the Water and the Land rainfall or frost outlook, for information about the likelihood of short term events that may have an impact - good or bad - upon farm operations.
  • Watching the Bureau's official warnings that may alert you to significant short term events that may affect your farm.

These actions are, of course, conducted in terms of all other aspects of the farming operation (e.g., price for your commodity, the cost of fuel, debt levels, etc.), and within the long term plan for the farm.

Longer-term climate cycles

As part of a long term plan and its risk management, it's also worth taking a long term view of ENSO. That is:

  • typically there will be at least a couple of El Niño and La Nina episodes in each decade - it is unlikely that a single El Niño or La Niña episode will last much longer than 12 months, though occasionally this has happened;
  • assume that each event will give a slightly different outcome at your location, as while events may be typically wet or dry, no two El Niño or La Niña events behave in exactly the same way;
  • recognise that using the rainfall and temperature seasonal climate outlook probabilities associated with El Niño and La Niña in your vicinity will give a better long term outcome than ignoring ENSO altogether.

Climate change

It's also becoming increasingly important to understand what may be changing in the background state of the climate, and hence the average climate for your region over which the ENSO impacts apply. This may mean spending a little time, for instance, examining the Bureau of Meteorology/CSIRO 'Climate Change in Australia' report, to become aware of what climate change may mean for your region, and hence factoring that into your ENSO calculations. In other words, will the 'average' years be warmer or drier in the future? Or is your area already undergoing a warming, cooling, drying or wetting trend?

Decision making before and during ENSO events

To manage the risk that the extremes of ENSO may raise, it is important to understand how El Niño and La Niña events typically behave once they develop, and to place these typical features in the context of your farming operations.

A typical El Niño episode

The following diagram shows a timeline through several seasons of some features associated with a fairly typical El Niño episode and its impact over Australia. In this example, the Southern Oscillation Index (SOI) is used as a measure of how strong the event is. Sustained negative values of the SOI often indicate El Niño episodes while sustained positive values are associated with La Niña. The table beneath the graph shows examples of decision points during the calendar year, relative to the typical El Niño features. The graph illustrates that ongoing monitoring of the climate situation, as described above, can be useful as the agricultural season or year progresses.

Examples of decision points during the calendar year
Summer Autumn Winter Spring Summer

Markets and buying considerations

General watch on global markets and global climate patterns

Cultivar choice

Stocking rates

Mix of activities

Fertiliser decisions

Planning for selling, harvesting, shearing, etc.

Fodder needs, haymaking, options for extra plantings, market options

Soil moisture

Check for summer management options

A typical La Niña episode

Similarly the diagram below shows a timeline of some features associated with a fairly typical La Niña episode. It is worth noting that La Niña is not the mirror image or precise opposite of El Niño, neither in its timing during the calendar year nor the geographic extent of its impact on Australia.

It is important to gain insight into the typical effects that La Niña and El Niño events may have for your location; it may well be that the influence is either not as strong, or conversely, even stronger than you think.


For more detailed explanation of the ENSO patterns, see the Australian Climate Influences page, and the maps of the impact upon Australian rainfall of past El Niño and La Niña events.

Other climate influences

There may also be other factors that affect your location that need to be considered, such the Indian Ocean, or the current state of the Madden Julian Oscillation. Managing the risk that ENSO provides is best started with understanding how important ENSO is for your region, and similarly, what other weather and climate factors need to be considered if an event is in progress. For instance, in 2007 a La Niña event looked highly likely but as it was developing, cool temperatures in the Indian Ocean formed suddenly during winter; the opposite of what typically occurs. This event appeared to have a negative impact upon rainfall over much of Australia, despite occurring during a period of La Niña formation. Knowing that the Indian Ocean sea surface temperatures impact your location, and being aware that the Indian Ocean effects are included in the Bureau's seasonal climate outlook forecasts, may have helped some users during this unusual event.

Climate monitoring and seasonal planning

Given that El Niño and La Niña:

  • have fairly typical lifetimes;
  • influence the likelihood of various weather phenomena over much of the Australian continent;
  • sit on top of the longer term changes being observed in our climate;

monitoring the state of the climate can assist with a number of on-farm decisions from the seasonal scale out to about one year.

ENSO graphs
Typical timelines for El Niño and La Niña episodes

Sample of management questions for seasonal to annual timescale decisions

  • Can I manage during the lower ENSO skill period early in the year? If so, what strategies should I use to reduce my risk?
  • If autumn has been wet/dry/normal, how does this affect planning for a normal year or an ENSO episode?
  • What is the chance of an earlier than normal autumn frost?
  • What is the chance of hot days but cold nights during and El Niño winter at my location?
  • My crop has survived a dry spell; what is the forecast for spring/summer rainfall and any impact on harvesting?
  • What is the chance of a spring frost?
  • What is the outlook for summer temperatures?
  • What typically happens in autumn following an El Niño year in my location?
  • Are there good opportunities for pasture restoration any time in the next few months?

Decision support tools

Decisions support tools - some of which are available from the Managing Climate Variability web site - are now commonly used to guide farmers through the seasons. However, even without such tools, a simple decision table can help to clarify the various options related to the climate. An example of how a decision table can be used to explore options for wet, dry or normal seasons is given below. A number of options can be quickly explored in broad terms.

Seasonal decision table for rainfall and exploring particular enterprise options.

Enterprise options

Rainfall categories

Under these conditions costs(C) and return (R) could be:

Net result/profit (P) (rainfall consideration only, excluding other factors)

Include a realistic range that could be expected

Check seasonal outlook for most likely rainfall category

Determine most likely profit range

Crop x
Herd y
Management strategy z

Wet range



<P1-a to P1+a>




Normal range



<P2-b to P2+b>

Example rainfall range

<P2-b to P2+b>



Dry range



<P3-c to P3+c>








The ranges a,b,c can be based on information about past returns and knowledge of the particular activity


Compare with other enterprise options to help choose enterprise management for the year

Useful weather and climate information

While far from comprehensive, the following list provides an outline of useful questions to ask about your location, and links to information that may help you find the answers, to help understand and manage the climate risks relevant to your farm.


For much of Australia, ENSO, and its extremes of El Niño and La Niña, are the dominant influence upon our climate. To manage the risks they raise it is worthwhile becoming familiar not only with their behaviour, but also with a number of tools that can help once an event is underway.


Additional Reading

Weather Derivatives

Managing Climate Variability site

This page is produced with the support of Managing Climate Variability - a consortium of primary industry research and development corporations.