Christchurch fire crews are fighting a wildfire on Governors Bay Road - while a helicopter is on standby.

The very hot and windy conditions on Thursday, combined with access difficulties are proving a challenge, a fire spokeswoman said.

The public are asked to avoid Governor's Bay Road, near Cass Bay, as the fire is burning gorse near the top of the hill. No structures are currently at risk.

Fire crews are also dealing with a number of smaller fires in Selwyn and north of Christchurch, the spokeswoman said. Meanwhile, high winds in Christchurch has seen more than 2800 Orion customers left without power on Thursday around 2pm.

The winds have caused trees and branches to fall through power lines, cutting power in a number of rural areas.Rural locations are mainly affected including Lincoln, West Melton, Tai Tapu, Akaroa and in Lyttelton. The strong winds have also led to a truck and trailer being blown over on State Highway One near Dromore Road.

The road is closed and local diversions are in place. Further north in Leeston, a tree is blocking the southbound lane of Leeston Road near Chamberlains Ford.