Children and young people are preparing to walk out of lessons and lectures, with hundreds of thousands of workers expected to join them.
For the past few months, youth strikers, unions and organisations have dedicated their time and effort towards this international strike.
It comes ahead of a climate action summit in New York convened by UN secretary general Antonio Guterres to urge countries to up their climate efforts.
Much steeper measures are needed across the globe to prevent temperature rises of more than 1.5C (2.7F) or 2C (3.6F) to avoid the worst impacts of climate change
As if to underline the urgency of the issues, the mercury is set to hit 26C this weekend - 8C above average for the time of year.
The UK Student Climate Network (UKSCN) says more than 200 events are taking place across the UK, with – for the first time – adults being encouraged to join the youngsters as they strike.
UKSCN is calling on politicians to bring in a “Green New Deal” to cut the UK’s emissions to zero and improve lives, changes to education to equip youngsters to deal with the climate crisis and votes at 16 to give them a voice.
Mayor of Greater Manchester, Andy Burnham told activists gathered in Manchester to 'ignore those who criticise their protests'.
Protests are also taking place across the Isle of Man. The [**protests are being held outside Tynwald**](http://Manx students join protests demanding climate action from the IoM Government) as pupils demand that the Government make commitments to tackling climate change.
Our Correspondent, Mel Barham has this report on today's events: