Hundreds of students and other climate change protesters will march from Hove Lawns through the city centre to the Level on Friday.
Sussex Police is warning there may be disruption as it is expecting a “significant” number of demonstrators to take part, with the council sending schools guidance on allowing pupils to attend should they want to.
This is the latest in a series of marches inspired by Swedish student Greta Thunberg, who kicked off her campaign by missing every Friday.
The city’s secondary schools are being asked to get a member of staff to accompany any pupils going on the march, and primary schools asked to ensure parents collect them from school.
Sussex Police have also asked schools to show pupils an Instagram video which explains the police’s role during protest marches to avoid unnecessary conflict.
Among the marchers will be council leader Nancy Platts and opposition leader Phélim Mac Cafferty.
The march is set to form up at Hove Lawns at 10am, where the crowds will be addressed by Caroline Lucas MP.
It will then move off at 11am via Brunswick Road, Western Road, North Street and the Steine to The Level, where campaigners including Green MEP Alex Phillips will speak.
The route was organised with the help of the GMB Union, which helped protesters liase with the police.
Superintendent Chris Veale, who is leading the police operation for the event, said: “We are engaged with the protest organiser and will work with them to facilitate a safe and peaceful protest, while endeavouring to keep disruption to the city to a minimum.
“However, it is anticipated that there will be delays as the protest moves along its route from Hove Lawns to The Level and anyone planning to be driving or using public transport in the city centre should be aware that their plans may be affected and allow themselves extra time.
“As with previous protests of this kind, it is anticipated that there may be a significant number of younger people taking part. Their participation is entirely a matter for their parents or guardians and educational establishments as to whether they may be permitted to absent themselves.
“However, as this may be the first experience of such an event for many of them, our youth safety intervention officers have reminded secondary schools of a national policing Instagram video aimed specifically at young people to explain the police’s role.”
Meanwhile, more than 300 Brighton and Hove parents have signed an open letter supporting the climate strike.
It says: “Greta Thunberg and the Youth Strike 4 Climate movement have inspired millions to take to the streets to call for real action on climate.
“We do not have time to waste and as parents we fully support our youth in their demands for a safe climate future.
“Given that Brighton and Hove council have declared a ‘climate emergency’ we are acting collectively and will not recognise threats of unauthorised absence or fines on this day of action.”