Lorraine Grains, 43, from the Vidlin area in the north east of the mainland, was reported missing on Thursday.
Local residents have joined police, coastguard ground teams and the coastguard search for the woman.
Volunteers have been asked to be careful while out searching in wet conditions.
Inspector Martyn Brill said: “We would like to thank the volunteers for their support - it is very much appreciated.
“I would ask if you do want to volunteer your help then make sure you are well equipped, wearing suitable clothing and prepared for the conditions.
“I know everyone offering their help is doing so with the best of intentions but we do not want people to put themselves at risk.
“If anyone finds anything you think is notable, then please leave it in place and inform police or coastguard personnel.”
Lorraine is described as being about 5ft 2in tall and of slim build.
She has long purple hair and is believed to be wearing black leggings or jeans and a long black overcoat.
Inspector Brill added: “We are concerned about Lorraine’s welfare and as such I would urge anyone with information which could assist us passes this on.
“Please contact Police on 101, using reference NL680/18, or speak to any police officer.”