The action started at 15.30 in Vērmanes garden, well after lessons have finished, and saw protesters march to the Rīga City Council and then the Saeima building via the November 11 embankment.
"This is important. This is very important. It's more important than most of us feel about it day by day," said Marija Luīze Meļķe, 21, a poet.
"Climate change is happening, and not enough attention is being paid to it. And this is a step to make people more aware if it and help them understand that it's happening," said Henriks Zēgners, 23, head of the Satori culture portal.
The global protests have been inspired by teenager Greta Thunberg, who protests every Friday outside Sweden’s parliament to urge leaders to tackle climate change.