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Melissa Ewings was reported missing on Monday when she didn't turn up to work and her family say they have serious concerns for her welfare.
On Sunday the 31-year-old told a friend she was going for a walk to the Clarence River, near Kaikōura, but has not been heard from since.
Police officers and Land Search and Rescue volunteers have been searching the Clarence Valley to find her.
LandSAR CEO Carl Mconie says volunteers were actively involved in the search efforts but referred queries on the search operation to police.
MetService meteorologist Lewis Ferris says conditions in the area were "very settled" over the last weekend, with nothing of note weather-wise near the Clarence Valley.
"From yesterday there were strengthening northwesterly winds and rain from the west in that region in the afternoon, possible overnight," he said.
"A northwesterly is not a very cold wind, but if it is very strong or in an exposed area, it can be harsher."
While MetService didn't have any temperature readings for the Clarence Valley, nearby Kaikōura recorded a warm 23C at the local airport on Saturday.
"Sunday had a high of 15.8C and Monday had 17.9C, so definitely not cold daytime temperatures, bur overnight it was getting below 5C, so there was a possibility of some frosty conditions in sheltered areas," Ferris said.
According to Environment Canterbury the river's currently in flood - and was flowing at a high of 60 cubic metres a second on Saturday.