Rain is set to deluge Northland ahead of the Auckland Anniversary weekend, with flood-threatening subtropical downpours and thunderstorms forecast to hammer the region.

MetService has issued an orange heavy rain warning for Northland from 10pm tomorrow, just as droves of Aucklanders will be making their annual exodus northward.

The warning is in place until 10pm on Friday.

Bad weather in Northland forecast. 12th July 2021 Northern Advocate Photo by Tania WWhyte

MetService expects up to 130mm of rain, especially in the east and north and said thunderstorms are possible.

Peak rain rates between 10 and 20mm per hour are expected.

“Heavy rain may cause streams and rivers to rise rapidly. Surface flooding and slips are also possible and driving conditions may be hazardous,” MetService warned.

MetService meteorologist Peter Little told the Herald earlier that a low-pressure system was developing in the subtropics this week and would eventually move south towards the country.

“I think what we could say for [Auckland Anniversary Weekend] is that there will be easterlies, and that it will be quite humid,” Little said.

“It’s really back to that muggy sort of weather that has, unfortunately, been really common over the north this summer.

“It’s also probably going to be quite showery, particularly in Northland, where there’s a risk of heavy rain.”

For parts of Auckland, he said, things may be different.

“Much of the city area and southern parts of Auckland may end up having reasonably good weather if they’re sheltered – and obviously the Coromandel Peninsula can provide good sheltering too.”

Currently, MetService is forecasting rain, with some heavy falls and strong easterlies for Auckland on Saturday. The forecast high is 23C.

Moving into Sunday, rain is expected to ease over Tāmaki Makaurau and there will be strong northeasterlies. The forecast high is expected to be 25C.

On Monday, expect a few showers.

MetService is forecasting rain for Whangārei from tomorrow through to Saturday, with rain clearing on Sunday. The forecast highs for the period are expected to range between 22C and 25C.

However, the forecast for Monday appears to turn again with showers expected.

The forecast looks much the same further north for Kaitaia except for on Monday when it is expected to only be cloudy.