Environment Minister Peter Gutwein said, while the state strongly encourages young Tasmanians to stand up for what they believe in, it would be preferable for students on a school day to be at school.

Ms O'Connor said the Australian Capital Territory government had formally shown its support for the School Strike 4 Climate rally and urged the Tasmanian government to do the same.

Hundred of students across the state turned out to rallies in March this year demanding governments stop using fossil fuels, bring in 100 per cent renewables by 2030 and cease work on the Adani mine.

"We need the Tasmanian government to come out and make a strong statement ... to let the kids who are extremely stressed know their government is behind them," Ms O'Connor said.

"We would like to see for the first time the Premier and some of his Liberal colleagues there.

"They have been a notable absence. The kids are noticing it.

"The kids need to know that all their leaders are standing with them and are putting ideology aside [and] are prepared to act."

Labor environment spokeswoman Alison Standen said she would be attending the rally.

"Labor supports young Tasmanians showing leadership on climate change," Ms Standen said.

The climate strike will be held worldwide on September 20 with rallies to be held in Launceston, Burnie, Devonport and Hobart.