Parts of Canterbury have been drenched overnight

MetService's Orange Heavy Rain Warning for eastern Marlborough south of Ward and Canterbury has been lifted this morning.

The State Highway One Bridge over the Ashburton River has also reopened after being closed as a precaution.

Meteorologist John Law says a lot of areas have had more than their normal amount of rainfall for July.

He says Christchurch has had 142 millimetres of rain this month, more than double its average of 61 millimetres.

Selwyn Huts residents were urged to self-evacuate last night, as an incoming tide and rising river levels threatened to isolate people.