An estimated 20,000 protesters marched from Town Hall to Hyde Park on Wednesday evening, taking over George Street to demand stronger climate action as bushfires continue to rage across the state.

The event, titled "NSW is Burning, Sydney is Choking - Climate Emergency Rally!", was swiftly set up on Facebook last week by Extinction Rebellion, Uni Students for Climate Justice, and Greens MP David Shoebridge, in response to horrendous air conditions and ongoing bushfires across the state.

Thousands of protesters gathered at Town Hall on Wednesday. Credit:Wolter Peeters

Buses were diverted away from Elizabeth Street and Park Street because of the march, with some buses delayed by up to 30 minutes and more than 60 routes affected.

After a series of speeches, the crowd began marching down York Street at 6.40pm, before turning onto Park Street and heading east towards Elizabeth Street and Hyde Park.