MetService has upgraded its rain watch in Bay of Plenty to an orange heavy rain warning.

Areas west of Whakatāne, including Rotorua, could expect 100mm to 140mm of rain in the 24 hours from midnight tonight.

Streams and rivers may rise rapidly with surface flooding, slips and difficult driving conditions possible.

Showers were expected to develop in the region this morning, turning to rain this afternoon, possibly heavy, Metservice said in its latest weather update.

Northeasterlies were forecast to pick up this morning.

A heavy rain watch is in place for areas east of Whakatāne between 6am Wednesday and 11am Thursday.

MetService said it was also monitoring two tropical cyclones currently active in Pacific waters.

Spokeswoman Heather Keats told Ryan Bridge TODAY that Cyclone Vaianu, currently northwest of Fiji, is set to hit the North Island this weekend.

“As it gets upgraded, it will then drop into our neck of the woods ... it’s looking to track directly over Northland and Auckland and will have likely have quite an impact on New Zealand.”

Keats said Vaianu was currently a Category 2 storm but was likely to be upgraded to a Category 3 – or higher – by this afternoon.

“When it comes down over Northland and Auckland this weekend, it will hold its Category 2, which is highly unusual.”

Another cyclone Maila, Category 3, is currently slow-moving in the Solomon Sea, which Metservice says “won’t have any bearing on New Zealand weather”.