The Brynderwyns detour via Kaiwaka-Mangawhai Rd has been closed due to flooding and slips.

Waka Kotahi is now advising light vehicles to detour via SH12 and Paparoa-Oakleigh Rd, rather than Mangawhai/Cove Rd.

Kaipara District Council is advising motorists to stay off the road and avoid travelling on all routes between SH1 and Mangawhai due to the heavy downpour.

Deep flooding has been reported by social media users at Hakuru, and surface flooding in Kaiwaka.

MetService issued a severe thunderstorm watch for southern parts of Northland this morning that expires at 10pm. The weather service warned of localised downpours of 25-50mm per hour.

Devich Rd bridge underway during this afternoon's torrential rain in Mangawhai and surrounding areas. Photo / Supplied

Heavy localised downpours have been reported in parts of Northland, including 24.6mm in one hour between midday and 1pm, at Marsden Point.

Locals in the Mangawhai area are reporting some of the “heaviest rain they have ever seen” on social media as more wet weather batters the area. Multiple main roads are now flooded after just an hour of rain. Another local reported seeing emergency services helping those who are stranded.

Mangawhai ITM manager Rob Cook said everyone was on edge. ”We’ve got four of our staff who live in the flood zone, and they’re unsure if they can get home tonight.

”One lives in Kaiwaka and the roads are closed from here. ”I’ve seen nothing as bad as this in 20 years I’ve lived here. ”With the Brynderwyns shut and flooding out the other side of SH1 Maungatoroto way, there really is no access now. ”We can’t get north, we can’t get south, we can’t get anywhere. ”All these businesses are going to suffer because of the road closures.”

Mangawhai Books and Gifts owner Scott King said his customers could not get home again. ”We’ve had a couple of tourists asking for accommodation because they’re afraid they’re not going to get any further on their trip today.”It’s ridiculous. It’s the third time in four weeks this has happened.”

Mangawhai Golf Club general manager Carry Dale said her kids have been stuck at school for the last hour with no way to get home.”My kids are sitting on the bus at Otamatea High School and we have no idea how they’re going to get home. There’s quite a few kids stuck at school. ”The school closed an hour ago and they’re still there.”