The Rai River and its feeders have burst their banks this morning, causing surface flooding in places on State Highway 6 in the Rai Valley. However, the road remained open.

Marlborough Roads senior assets manager Steve Murrin said 50 kmh speed restrictions were in place on the Rai Valley stretch of SH6 and he urged people to slow down and drive to the conditions.

Road crews were working on a slip near Momorangi Bay on Queen Charlotte Dr, which has limited the road to one lane. There wre also many small slips in Port Underwood and the Marlborough Sounds.

NICK LANIGAN Nick Lanigan lives across the road from a section of the Rongo River where a slip has come down from a forestry skid site over night. The river is now running across paddocks to get around the slip, he said. Mr Lanigan said he recorded 260mm of rain in the 12 hours to 7.30am today.

The rain was expected to ease this afternoon, Mr Murrin said.

Rai Valley Fire Chief Trevor Holdstock said the brigade had not yet been called out, but it was possible if the rain continued.

The Ronga Rd resident said the Ronga River, a tributary of the Rai River, had breached its banks when he got up at 7.30am today.

The river was across the road in five places, but the road was still passable, he said.

"It might not be impassable this morning, but the way it's raining now I think it it will be later today."

He had spoken to a valley resident whose rain gauge had recorded 250 millimetres overnight.

He hoped the heavy rain forecast for today had come through during the night and would begin to ease off soon, but it was still steady about 10am.

Rai Valley dairy farmer Faye Leov said her Bulford Rd property was cut off by by the Rai River which had burst its banks in the night.

The river was beginning to merge with a small creek that runs in front of their house; almost all the paddocks in front of the house to the road were covered with water, but State Highway 6 was still open, she said.

"It's just a year ago that we had the really major flood - it was yesterday a year ago."

The rain hadn't eased and it was looking like another major flood could be on the cards, she said.

"I've seen it much worse, but at this stage it's not looking good because of the fact that it's not stopped raining."

They moved the cows to safer ground last night after the weather warnings were issued, she said.

"We managed to milk this morning, but if the river keeps rising we won't be able to this afternoon."

The floodwaters will cause a lot of damage to the pastures and a big mess would need to be cleaned up, she said.

Mount Richmond Motels and Foresters Cafe owner Robert Stillion said the Brown River, another feeder to the Rai, had burst its banks overnight and had flooded a field.

He was not concerned about flooding on his property because it was on a plateau overlooking the Brown River. During last year's floods the motel was cut off for several days he said.

Pelorus campground manager Nobby Neal said all of about 60 campers had left the DOC campsite overnight, but he expected more campers to arrive filling up the campground again today.

Campers at the powered sites were sticking it out, he said.

"A lot are saying they will find some sunshine," he said.

That will prove to be a difficult task, with much of the country experiencing heavy downpours.

Mr Neal said the downpour was nothing like December last year when campers were evacuated from the campground after it flooded.

"We've still got about three or four metres before [the river] will come into the campground."

He emptied his rain gauge this morning which had collected 118 millilitres since yesterday morning

Havelock Motor Camp manager Pauline Pickering said the grounds had a bit of surface flooding, but not as bad as last year.

"It's quite a heavy drizzle - it's more annoying than anything."

The forewarning of the weather front gave her and husband Neville time to plan. They had been careful about placing campers and put them on higher ground rather than in the hollows.

The sports pavilion was also opened as a day base for people to use to dry clothes and the laundry was also busy.

Two tourists had picked up their tent with everything it in and placed it on the concrete and under the shelter by the kitchen and were quite comfortable, she said.

"We've been through worse. We've been through much worse."

Roads affected by the rain in Marlborough at 11:00am Friday:

- Queen Charlotte Dr down to one lane after slip near Momorangi Bay

- A number of small slips on Ronga Rd, Rai Valley, which leads to Okiwi Bay

- Several small slips on Port Underwood Rd

- Surface flooding on State Highway 6 near Rai Valley and Ronga Rd, 50 kmh speed restrictions

- Tree fallen on French Pass Rd, between Okiwi Bay and French Pass. Residents have cut an opening, the road is open and road crews hope to clear it today