Mrs Forde left the Republic of Ireland in March to go travelling and before going to the Western Isles spent some time in Edinburgh.
When last seen, she was wearing an orange top, a dark jacket with white lining, blue trousers or jeans, walking boots, a cream/grey tammy hat, spectacles and was carrying a backpack.
A police spokesman urged people to call 101 if they have seen her or know where she is, adding: “If anyone has seen Susan or knows her whereabouts, please get in touch with Police Scotland, quoting incident number 1262 of November 2 2022.”
Missing Irish woman last seen in Stornoway travelled 15 miles north by taxi