Civil Defence crews in the Bay of Plenty will be out at first light to assess the full extent of damage caused by flooding, slips and high winds.
Bay of Plenty Civil Defence said there had been power outages in Whakatane, and many trees were down on roads throughout the region.
Some roads had been blocked by slips and falling powerlines.
A NZ Transport Agency spokesperson said many roads would remain closed in the Bay of Plenty and Waikato after Cyclone Cook.
State Highway 29 across the Kaimai Range is closed by a large slip at the bottom of the Waikato side and was not expected to open tonight.
Several roads in the eastern Bay of Plenty were closed because of power lines down and slips.
"All the closures will stay in place overnight and contractors will be out on the state highway network at first light assessing any damage and beginning work where they can," the agency said.
People should report any further damage to 0800 4 HIGHWAYS (0800 44 44 49) and should check the NZTA's website for updates as roads opened.
Bay of Plenty Coast fire region assistant area manager Kevin Cowper said the number of weather-related calls had slowed down by 8.45pm in the northern part of the region from Paeroa to Tauranga.
"We are still fielding a few calls in Tauranga City and in Papamoa but definitely not the numbers of callouts we had earlier in the evening," he said.
Cowper said fire crews were still out in Whakatane, Ohope, Edgecumbe, and Opotiki dealing with weather-related calls, but it seemed the region was over the worst of the storm.
Some of the road closures
SH2 between Ohiwa Beach Rd and Opotiki
SH34 at Otakiri between Edgecumbe and Te Teko
SH30 between Thornton Rd and Awakeri
SH2 near Pikowai camping ground on the Matata straight
SH2 Edgecumbe, SH2 at Waimana Gorge, and SH2 Pekatahi Bridge also remained closed.
SH25 -Thames Coast Rd from Tararu to Preece Pt because of several slips.