Understanding weather and climate

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.