Understanding weather and climate
Victorian farming communities and businesses know that we have always had fluctuations from wet seasons to dry.
So what makes the difference between wet seasons and droughts? And how is the climate changing over time?
Victoria's Climate 101 – A short animation of the latest science on our changing weather patterns
This animation provides a quick snapshot of the key drivers of Victoria’s rainfall and variability, recent trends and the latest science on climate change in Victoria.
It’s a useful discussion starter for agriculture. Show or share this and then have a discussion about what some of these changes might mean for your farm or business, and what types of actions you can take to manage climate risk.
Victoria’s Rainfall Snapshot – Animation
Unless you came down in the last shower,
you’ll know there are three types of annual rainfall in Victoria.
Too little. Too much. And everything in between. Been that way since records began.
Other types of variance are more recent.
In the past, a front off Perth during the cooler months,
would pretty much guarantee rain across Victoria a few days later. But doesn’t anymore.
The state’s autumn and cool season rainfall has also become less reliable.
Will these changes change? Or are they here to stay? Here’s what we know.
The fundamentals still apply.
Our rain still starts out as moisture from the oceans.
Dry years, that moisture’s in short supply.
Wet years, the supply’s too plentiful.
For moisture to become rainfall, we still rely on the same triggers, too.
The week to week battle between the high pressure systems, and cold fronts
But here’s the thing.
For the last 60 years, scientists have been observing those triggers.
Their measurements show Victoria’s cold fronts are increasingly shifting south,
impacting our cooler season rainfall.
And that our high-pressure systems continue to strengthen, impacting autumn & winter rainfall.
Scientists have also observed that temperatures across our state are rising.
Especially in spring. And that the last decade was our warmest in a hundred years.
The outlook is for this trend to continue.
There’ll be seasonal and annual variations of course
But basically, each new decade is likely to be warmer than the last.
To understand how this might affect rainfall, scientists developed not one,
but dozens of different climate models.
Their analysis shows different parts of Australia will be impacted in various ways.
Basically though, as greenhouse emissions trap more heat and things get warmer,
our climate zones, seasonality and weather patterns will slip southwards.
That means less effective rainfall, on average, in southern parts of Australia.
A warmer world is also likely to compound Victoria’s traditional rainfall variability.
That means more years when there’s less rain than in the past.
Punctuated by periods when there’s too much.
When it does rain, it’s also likely to come in shorter, bigger bursts,
because a warmer atmosphere can hold more moisture.
A warmer world won’t eliminate extreme cold though.
So, we’ll still have to deal with the risk of frost and cold outbreaks.
Increasingly variable seasons will present today’s farmers with future challenges, no doubt.
And collectively we have new technologies and solutions that we’ll need to get on with,
As we manage the risks of a changing climate
And successfully grow the future of Victorian agriculture.
A guide for farmers in using seasonal forecasts in South Eastern Australia
This booklet draws on the knowledge and experiences of grain farmers, advisors and researchers around how and when seasonal forecasts can aid you in making decisions about your farm enterprise.
Included are 10 case studies of growers and other useful information on using seasonal climate forecasts in south eastern Australia.
The booklet is a joint initiative of the GRDC and Agriculture Victoria using seasonal forecast information and tools to manage risk and increase profitability in the Southern Region project.
Download the booklet from the Growers Using Forecasts page on the GRDC website.
The Climatedogs animation series is an award winning series of short animated videos produced by the department. The animations explain what drives the climate in Victoria, and how climate drivers are changing over time. The Climatedogs were awarded the 2011 SCINEMA prize for Best Short Film. An international prize celebrating films that raise public awareness and trust in science.
In the spring of 2010, we saw the start of a much wetter season brought about by a combination of both La Nina (Enso) and the IOD (Indy) being in a negative phase, herding more moisture and big rain in southeast Australia.
More recently in 2015 we had Enso bring us an El Nino which brought about some very dry conditions in parts of Victoria. Also the pressure pattern was very high in 2015 due to Ridgy, who has been delivering stronger pressure patterns over parts of southern Australia over recent decades.
Sam herds up our cold fronts but in the past decade, he has been doing that a little less often which has meant we missed out on a few rainfall events during our cooler season.
In 2016 the winter and spring has been more favourable due to Indy being is it's wetter phase (IOD negative).
- See how the climate drivers work together to bring rain to Victoria
- Enso rounds up tropical moist air in the Equatorial Pacific Ocean
- Indy delivers moisture from the Indian Ocean
- Sam influences the strength and frequency of cold fronts over Victoria
- Ridgy and high pressure systems can block rainfall in Victoria
- Eastie's deep low pressure systems can dominate annual rainfall in Gippsland
Learn more about what drives rainfall in Victoria
To make it rain in Victoria a source of moist air is needed, which mostly comes from the north, followed by local weather conditions to promote rainfall. For example, cold fronts crossing Victoria from the south often trigger rainfall when they meet warm, moist air.
This process is caused by different climate drivers that influence Victoria's wetter or drier years. Climate drivers vary over the months and years to influence our seasonal rainfall. For example, our driest years have been when two or more of these climate drivers have been in their 'dry phase' at the same time.
Select one of the following climate drivers to learn more about what drives our wet and dry seasons: