Is MetService the most accurate

For Canterbury, I rely on both Canterbury Weather Updates and Canterbury Snow and Weather Watch. Both are far more detailed and accurate than Metservice. Can't help if you're outside of Canterbury though sorry.

Again for Canterbury I use METVUW to get a rough overview 10 days out, then compare that with Weather Underground 10 days out. Closer to time I compare them with the forecasts on MetService (AP, Canterbury High Country and Hokitika) and any warnings etc I also use the rainfall and river flow monitors on the ECAN website. (Waffle removed 😊)

Agree the Vic Uni Metvuw site's maps give you far more idea what's going on than the pretty pictures & text on metservice for a 10 day forecast. Metservice must have far more processing power in their hands so it's a shame they don't give 10 day weather maps. Noone expects it to be spot on 10 days out but the sequence of maps lets you assess all the possible outcomes.

yr.no is another good weather website, from Norway. I find this website tends to underestimate windspeed at altitude though but otherwise seems pretty accurate out to 4-5 days. You can choose a location as precise as individual peaks e.g. Tararua Peaks. Generally I look at yr.no (yeah nah), Metvuw, Weatherunderground, and the mountain forecasts from Metservice and take the worst weather from all of them and plan accordingly.

yr.no looks quite good. Must be a database of major meteorology services from around the world

There are a number of data models (atmospheric, oceanographic) that are used to generate global weather forecasts. Data comes from a myriad of sources, globally. What does 'looks quite good' mean? The presentation is nice? or the forecasts seem accurate? In past years, I've looked at forecasts from this and a few other sites over a few weks - several times. Yr.no is not the worst but accuracy (and consistency) of forecast varys from marginal (3 days out) to worthless (7+ days out). If you want to evaluate the forecasts, you need to record what it's telling you and see how that varies over the forecast period and how each successive forecast compares to the actual weather experienced. You'll be surprised, I think. Really, imo, regional weather forecasting organisations are going to be more accurate than global ones because they moderate the models' predictions with local knowledge. NZ is a small mountainous landmass - accurately and consistently predicting which catchment(s) will get rain, and how much, is pretty close to impossible - even one day out. All that said, nzbazza has it nailed - read the available info, pick the worst bits and plan for that :smile:

I think yr.no is Norway's equivalent of the NZ Metservice, a government owned/run weather service. I remember a meteorologist/weather forecaster from Metservice giving a talk at the club a few years ago that mirrored what @bernieq said above, they use a number of different global models along with their own data and models, and then moderate what those models said with their own human experience of New Zealand. At the time of the talk one issue with global models was their granularity was low, meaning each data point covered an area of something like 10km x 10km. I imagine as computing processing power has increased that granularity would of reduced, hopefully making for a better model. Crowded House summed it up best "Four seasons in one day".

yr.no is just computerised forecasting for countries outside of norway and still highly falable. metservice offers human forecasting for NZ as well as various other local services like weatherwatch. they are specialising in focusing on local weather and have a better understanding of NZ weather. still not perfect, but overseas services just broadcast whatever the computer model spits out without anyone moderating the result... don't trust a weather forecast completely, take more gear than the forecast tells you you're likely to need... to a certain extent i wonder how much forecasts can lull people into a false sense of security. esp if you want to go as light as possible. the forecast says its going to be good weather , so i'll take stuff all clothes so i can go light... nz's weather is hard to forecast because we are surrounded by a lot of ocean and we don't have a lot of accurate data coming in about conditions around Nz and the weather changes as it hits the land... i've seen weather warnings issued by local agencies as severe weather actually happens. i see people today in the hills with only the gear for the forecast for the time period they are expecting to be in the outdoors and they end up sailing very close to the wind as they can end up racing against deteriorating weather.... no extra clothing in a pack, no emergency shelter. just summer running gear. some of these people scoff at experienced trampers with their big packs on and how much slower they are... but your pack is your lifeboat... it's all you've got if things go wrong sometimes.. no guarantee a helicopter will get to you in time if you get caught out in bad weather.

I often compare MetService with snowforecast.com and find MetService are usually more pessimistic with the rainfall. Weather Underground is great for little local forecasts e.g. we used the Cass forecast for going up the Andrews in Arthurs Pass and figured Cass might get more rain from weather travelling up the Waimak so decided to deduct some of the rainfall intensity (0.1mm to 0.2mm per hour)from the Cass forecast. Turned out pretty much so. Barely spitting in the Poulter. Must bookmark some of those sites mentioned for Canterbury!