He also said it was likely areas that had experienced flooding in recent weeks could see the same overnight.
The soil in some areas was already saturated making it difficult for water to drain into the ground, he said.
Rotorua has already had 213.2mm of rain this month compared with a total July average of 133.9mm.
Tauranga had 200mm compared with a total July average of 123.6mm.
On Monday Emergency Management Bay of Plenty spokeswoman Lisa Glass said the Bay of Plenty Regional Council flood teams were keeping a close eye on river levels.
"This predominantly affects rural residents- when the rivers reach certain levels, automatic messages go out to relevant land owners."
She said in towns and cities there was a risk of surface flooding and all the associated issues - roading damage, low-lying areas flooding, as well as landslides and slips.
"So much rain over recent days means there is a risk of this sort of event, along with trees uprooted etc. With the sodden ground it may not take extreme winds to cause trees to fall."
Tauranga City Council manager drainage services, Radleigh Cairns, said the council was monitoring the weather closely and carrying out all their usual checks for when significant rain was on the radar.
An uprooted tree near St Mary's Catholic School in Tauranga this morning. Photo / Mead Norton
"A heavy rain checklist is made prior to any predicted event and is performed again at the end of the rain event. This is predominantly for inlets and outlets with a history of blocking with debris that is mobilised in a storm".
Meanwhile, Rotorua Lakes Council said usual preparations had been undertaken by the infrastructure team and contractors, with crews on standby overnight ready to respond to any events.
It urged people to take "extreme care" on all roads throughout the district as there was likely to be surface flooding, small washouts, tree falls and debris on the roads.
Pre-rain event checks on critical large culvert inlets had been completed to ensure all are clear of any potential blockages, it said.
A section of State Highway 25 between Coromandel and Te Rerenga was closed at 5pm yesterday and would not be opened until about 10am today due to a slip.
Meanwhile, a police spokesperson said police received a report at 7.15 on Monday morning that a track and trailer unit had rolled on Tower Rd in Turangamoana.
The driver was reported to be uninjured but the truck was blocking the whole road and towing was requested to remove it.
