Rain of up to 40mm per hour is expected this afternoon.
They are urging people to be alert and extremely careful on the roads.
The western Bay of Plenty has already seen a significant amount of rain, and it is now affecting the eastern Bay of Plenty.
Thunderstorms are predicted to hit this afternoon and this evening.
Bay of Plenty Civil Defence emergency management group controller Clinton Naude said all roads are open and no reports of flooding have come in yet.
"Mostly it's just really wet out there. This rain isn't over yet though and we encourage people to keep up-to-date with weather reports", he said.
Fightfighters across the area had been called out to arching power lines which had gone down.
This occurred in Papamoa at about 3.30am, Greeton at about 5.15am, and Waihi at 9.36am, according to Northern Fire Communications spokesman Jaron Phillips.
Tauranga City Council Communications Adviser Marcel Currin said despite the bad weather, there had not been much damage around the area.
According to Mr Currin there were tree branches on the road along Marine Parade, but it was cleared up in the early hours of this morning.
The band of heavy rain and thunderstorms is thought to move across the western Bay of Plenty at 8am, according to the Metservice.
It is then predicted to cross to the eastern Bay of Plenty.
A thunderstorm watch has been given to the Bay of Plenty, with the possibility of some thunderstorms becoming severe.
These severe thunderstorms could localise downpours of 25 to 40mm per hour or more.
Civil Defense urges residents to:
- Check that any drains and gutters around your property are clear so the rain goes where it's supposed to.
- Bring pets inside. Move stock to shelter.
- Drive with caution and if possible, avoid low-lying coastal roads.
- Keep up-to-date with weather forecasts.
- Check emergency food and water provisions.
Regular updates would be provided on Bay of Plenty Civil Defence Emergency Management's website www.bopcivildefence.govt.nz and on www.facebook.com/BOPCivilDefence.
