NZ: Heavy rain, gales, thunderstorms for some - but high pressure is tracking back this week

Added: 2026-05-05

[00:00:08]C. Hello, I'm Philip Duncan. It's Monday, the 20th of April. Thanks for joining me. Hope you had a great weekend. Well, we've got this large low kicking off this week. It was around all weekend out here in the Tasmin Sea, but it is going to drift slowly eastwards towards the upper North Island tonight and across Tuesday. It moves further out to the east. Now, as we said in our Friday video, expect the unexpected with a setup like this. Large lazy low producing areas with heavy rain, thunderstorms, and some large dry spells as well. So, there'll be some places where rainfall exceeds what is forecast and other places where maybe you thought it was going to be stormy than it was and it was actually quite sunny at times. So, that is the nature of a messy setup like this. And we've seen uh damage and flooding around Wellington.

[00:00:53]We've seen that tornado up around Bay of Plenty. So these are the sorts of things we can get with this sort of weather even though there are some large dry areas amongst it all. Now in the South Island, see the change that develops this evening. More of a southeasterly.

[00:01:06]So your temperatures are going to go down over the next day or two as this cold air flow gets dredged up thanks to the high pressure zone. West coasters probably quite sunny and dry. Certainly the further south you are, the drier it will be. But you got this squash zone between low pressure to the north, high pressure building to the southwest. And that makes for a windy southerntherly gale force southerntherly coming into Wellington and Cook Street, but it could brush Banks Peninsula and certainly likely to affect the eastern North Island. Maybe not so much tonight, but going through Tuesday as the center of that low moves eastwards. And with all that low pressure around the North Island, that's why that instability remains right across today and going into tonight. Now 9:00 tonight, center of the low right over the top half of the North Island, light winds. Um that can actually produce some showers with that instability that you've got, but you're seeing perhaps a higher risk of wet weather eastern side of the North Island, southern half of the North Island. And of course, that wet weather slides down into Canterbury, Malbor, even coastal parts of Otago. western uh areas though and the southwest and very southern areas probably quite dry if not completely dry going into that setup this evening. So we got a few different things going on but the wind and the rain in central New Zealand, the upper south island, the lower north island, that will be the main feature as we go into Tuesday. So the Tuesday lunchtime map also shows 24 hours of rainfall from today through to tomorrow. You can see the heavy rain on uh Canterbury up towards Malbra and inland parts of Canterbury might also get not necessarily heavy rain, but there could be a thunderstorm in there. Uh and the further south you go, the more that tapers off. But you are seeing wet weather chances in the South Island, mostly into the northeast corner, Malbra down towards Canterbury. But the bulk of the heavy rain looks to be around wided upper moving northwards towards Manawatu Tadua and going into Hawks Bay. 80 millimeter rainfall potential here in just 24 hours. And that doesn't include the chance of having one of those thunderstorms that could make it go a little bit higher. And further northwards, despite low pressure being sort of in this area around the top of the North Island and certainly out to the east here, um maybe not overly wet, but there is still the chance of some random downpours or thunderstorms. As we go to Wednesday, the energy is very much along eastern New Zealand, especially the eastern North Island, Hawks Bay, right down to Wanappa. There might be a wee bit of spillover going into Manowatu and Hot Feninoa. You've also got some wet weather um around the North Canterbury Malbra area into the mountains could be a few heavy falls and further south of that across much of Canterbury, the temperature drops because of that colder air flow being pulled in behind the low. So the low is moving away from us and southerntherly winds or southeasterly winds all the way along the eastern side of New Zealand down to about Otago and that's where those winds start to fade out. Once more western areas are mostly dry and remember this is 24 hours of rainfall.

[00:04:07]So if you're in the blue shaded area that's at the bottom of the scale but you could still have a heavy downpour or thunderstorm or even uh you know a severe thunderstorm warning issued by Met Service. Although we'd like to think by Wednesday that southeasterly flow will start to see things easing and by Thursday in comes the high. Quite a strong high pressure zone. It's quite large as well as you're going to see in a moment as we go into the weekend.

[00:04:31]Leftover cold stuff moving away but there will still be a cooler showery south tossoutheasterly wind along the eastern and north island wided up or up to East Cape. One or two showers might move over towards Great Barrier Island and Northland as we go through Thursday, but the rest of New Zealand is dry, certainly in the South Island. Light winds as a result of the high pressure zone, although sometimes the west coast can get a little bit of cloud out of that. So on Friday, really big area of high pressure. That's great timing for the weekend as well. It stretches down to the southern ocean. It stretches up towards Fiji, Vanoiru and New Calonia, the tropics of Australia and right out to Western Australia. So that is a really big high pressure system. Might be a few showers in the northeastern corner of the North Island and the very north. Um but other than that, it is a dry day with light winds in most regions and it stays like that going into the weekend. High pressure, maybe a bit of cloud coming into the north from the east here. So still a couple of showers around Great Barrier Island or Northland. the pale blue right down off the off the key almost. So, it's not going to be much. And we're also monitoring some some low pressure developing further to the north here on Sunday. You can see a subtropical trough which is the beginning of a low pressure zone, but it is running into this big area of high pressure which gets squeezed on Sunday. So, it's not as big north to south, but it's still big east to west. Now the southern part of the high pressure zone over here over the lower half of the South Island or in fact over the South Island westerly winds do start to return. So you got easterly and northern New Zealand westerly's from about Cook Straight southwards still a lot of high pressure bit of west coast rain might be an isolated shower or two but really it looks pretty dry as we get to the end of the week. So there is some good news light at the end of the tunnel. Keep up to date with all the Met Service warnings and watches and of course severe thunderstorm warnings. We do expect more of those to be issued across today, Monday, and potentially again going into Tuesday. I'll see you with our next video update. That'll be tomorrow, Tuesday. I'll catch you then.