How the Southern Annular Mode (SAM) Affects Australian Farmers

timothy Barratt

October 18, 2023

This article will give you a clear understanding of how the SAM affects Australian Farmers and the weather patterns that are associated the its interaction with other climate drivers.

Decoding SAM: The Unsung Hero of Aussie Weather Patterns

Hello again, dear Aussie farmers! Beyond the popular El Nino and La Nina, there’s another vital player impacting our climate: SAM, or the Southern Annular Mode. Let’s dive into understanding SAM and how it can help you navigate the farming seasons.

Introducing SAM

Ever noticed the belt of high pressure encircling the globe in the subtropics? That’s the subtropical ridge. To its south, we find the roaring westerly winds, often named the roaring 40s and furious 50s. SAM reflects the unusual shifts of these winds north or south.

How SAM Affects Our Weather

When these winds shift, they stir the pot! They can influence the weather systems around our southern hemisphere, which includes those bringing rains to southern Australia.

SAM’s Three Phases

Similar to our previous friend, the IOD, SAM has three moods: positive, neutral, and negative. They usually last about two weeks, but sometimes they stick around longer.

Winter’s Dance with SAM

Typically, the westerly winds sit atop southern Australia during winter. This invites cold fronts from the south, blessing us with regular winter rains. But if these winds wander towards Antarctica, we get fewer rains, a situation termed positive SAM. However, there’s a twist. A positive SAM can also lead to heavier rains on the East Coast.

Summer and SAM

In summer, things flip! If the winds venture north (a negative SAM), drier air blankets eastern Australia. However, a positive SAM means more moist winds along the east coast, which translates to a higher chance of rain.

SAM’s Moves in Spring and Autumn

In spring, SAM’s influence resembles a mild summer pattern for southern Australia. A negative phase can even hint at a potential heatwave. Come autumn, SAM’s influence on rainfall diminishes, but a negative SAM can usher in extreme heat in northern and central regions.

SAM’s Connection to El Nino and La Nina

SAM’s moves are linked to these famous climate drivers. During El Ninos, SAM tends to lean negative, and during La Ninas, it leans positive. This only intensifies their effects, especially in summer.

A Recent Trend

Lately, there’s been a drift towards more positive SAM events, causing weather systems to shift south.

What Does This Mean for Aussie Farmers?

Grasping the nuances of SAM empowers you to anticipate seasonal outlooks better. With this knowledge, you can craft strategies tailored to your crops, ensuring fruitful harvests.

Why you should be using CelsiusPro’s Weather Certificates to cover these risks.

If the IOD and Enso forecast are predicting wetter or dryer than usual conditions, you can combat the financial burden of these risks with our Dry Season or Wet Harvest Weather Certificates. Just give us a call or watch our tutorials and we can show you how to become financially independent from these events.

Wrapping Up

SAM might not be as famous as El Nino or La Nina, but it’s crucial in the grand scheme of Australia’s climate. Keep tabs on its rhythms to stay ahead of the curve. For a deeper dive into SAM, head over to

Here’s to savvy farming, rain or shine!

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