She said while some of the events will be online due to coronavirus restrictions "most will be physical, keeping a social distance".
In a social media post Greta said the strikes would be held "in over 2500 places around the world and counting!".
She also shared a map showing all of the different locations where events will be taking place.
The rules around gatherings in the UK are much more complicated than with the 2019 school strikes, due to coronavirus and measures like the 'rule of six'.
There are legal restrictions in England, Wales, Scotland and Northern Ireland about the numbers of people who can meet up outside.
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Millions of people in countries such as Australia, Ghana, Germany and the UK have since taken part in protests.
At the end of February Greta travelled to Bristol to take part in the protest there.
But soon after this, coronavirus and lockdown being introduced in many countries meant the protests had to be put on pause.
During lockdown Greta hasn't been able to campaign in the same way, but has spent time with family and catching up on schoolwork.
However, she was still able to raise awareness about climate change through social media and radio podcasts.