MetService issued a heavy rain warning for Wellington, the Tararuas, Kāpiti and Horowhenua.
Kāpiti Emergency Operations Centre duty controller Paul Busing said a community of about 25 properties had been cut off due to a landslip in Maungakotukutuku Valley.
An emergency welfare centre has been activated for people who won't be able to get home and the Red Cross has been called in, he said.
There had also been a "significant" landslide on private property north of Paraparaumu, he said.
Hutt City Council reported all remaining vehicles have been moved to higher ground and the car park will be assessed for reopening.
Between 60 and 90mm of rain was forecast for Wellington on Monday morning while Kāpiti, Horowhenua and the Tararuas were expected to get a whopping 100 to 120mm.