The rally and march started outside the Illawarra Performing Arts Centre in Burelli Street.

Before too long the striking students and their supporters made their way to Crown St Mall via Burelli St.

Along the way protestors chanted such things as 'what do we want? Climate justice. When do we want it? Now".

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Speakers also addressed crowds outside IPAC and the top of Crown St Mall and near Wollongong Town Hall, on the corner of Kembla and Crown streets.

One of the youngest speakers, eight-year-old Lilly Callaghan from Scarborough Public School, was especially popular.

"I believe we should take care of our planet because it is the only one we have. Me and my friends deserve a future. I believe the earth is worth more than money," Lilly said to the crowd who erupted in approval.

Estimated national attendance:

Laura Ivy Jean is only 14-years-old but she is "terrified".

"I'm constantly worried about about what opportunities there is to end the climate crisis. I'm anxious and conscious of every policy that the government puts out," she said.

The Wollongong student also struck a chord with the thousands of people who had gathered for Friday's School Strike 4 Climate rally, when she pleaded with the government to act on climate change urgently.

"This is the last time I ask you. This is the last time I plead for my future. This is our future, it isn't fair that you are killing it off," Laura said.

"We did not ask for this fight but we will fight it.

"We are fighting you because you have decided to ignore what will be humanity's demise.

"Let this be a warning, when our country no longer has any water left, when our land has dried up, when we do not have any land left to farm livestock, when fires burn through the country all year, do not say we didn't warn you, because we have warned you, we have been warning you since the very beginning..

"This is your warning. Start the change. We are the voice and we will be heard."

The Wollongong rally was one of many held throughout the country and backs the lead of Greta Thunberg and 46 other high school activists, who earlier this year penned an open letter calling for a Global Strike for Climate on September 20.

It started outside the Illawarra Performing Arts Centre in Burelli St at midday.

The festival atmosphere soon turned serious as speaker after speaker urged for urgent climate action.

Back in 2009 union organiser Martin Cubby was in the snowy streets of Copenhagen, Denamark protesting with 80,000 other people to demand climate change action.

"There has been no action ... in fact we are going backwards," he said.

"We must put pressure, constant, relentless, peaceful pressure on our political leaders and our business leaders to make sure they act in the next 10 years."

This view was shared by fellow speaker, NSW Greens MP David Shoebridge.

"We need to change the political system that allows the fossil fuel industry to buy its politicians. We do that, we will change politics, we will secure the future, we will win this fight for climate justice," he said.

Visibly emotional Lake Illawarra High School student Mikaela Amos told the crowd she was scared for her future.

She was also "angry and mad".

"We are sitting back relaxing while the effects of a climate crisis play out like a movie right in front of our eyes," Mikaela said.

"This isn't just a fixation of mine, this is a land degradation, fossil fuel invasion, greenhouse gas emission, an annihilation.

"There will be no more patience, there will be no more justification, we will fight for ourselves and for the future generation.

"Instead of watching a tragic film of a climate crisis, we will become actors that make a change.

"We are the aggravation for our planet and we will not continue to hide for a reputation, for we will start that conversation to restoration."

But Mikaela was "terrified" because she was part of the last generation that could stop this climate crisis.

"There is though hope for us all, and if we believe in each other, we can have a sustainable environment, we can have a future," she said.

"There is no time to pretend that we are living in a bubble, we will rise up stronger and if they want to shut us down, well they're going to have to go through all of us.

"The youth are rising, no more compromising."