South Island Met Agency (SIMA)

South Island Met Agency: Independent Weather Forecasts for the South Island of New Zealand

By the SIMA Forecasters · Published by South Island Met Agency

South Island Met Agency (SIMA) is an independent, private meteorological service run by two passionate forecasters. We publish hand written forecasts covering snow risks, convection forecasts, a daily Significant Weather Outlook, and more detail during significant weather events through our Regional Weather Notice forecasts. Our focus is the South Island of New Zealand: high-impact convective thunderstorms, alpine snow levels and mountain passes, and medium-range synoptic weather analysis.

Alongside our forecaster-written products, the site provides town forecasts for locations across the South Island, a 5-day synoptic weather briefing, atmospheric sounding trends, and live radar and satellite imagery, so you can follow developing weather in one place.

Our Forecast Products

Regional Weather Notice

SIMA Forecasters produce Regional Weather Notices to cover more detail when significant weather is likely for a region in the South Island. Each notice gives regional commentary and timeline context for the expected event.

Significant Weather Outlook

SIMA Forecasters produce a daily Significant Weather Outlook covering 5 days from today. Outlook maps show the likelihood of notable weather across specific South Island regions using three risk categories:

  • Slight Risk (10% – 30%): low probability of significant weather within the highlighted sector. Isolated or weak activity is possible, but confidence remains low.
  • Enhanced Risk (30% – 50%): moderate probability of significant weather. Localised impacts may occur across parts of the highlighted region.
  • High Risk (over 50%): high probability of significant weather, with potential for widespread or noticeable impacts. A Regional Weather Notice may be issued.

StormCast

SIMA Forecasters produce Regional StormCast forecasts for South Island regions when significant convection is expected within 48 hours, covering thunderstorm and severe convective weather risk.

SnowCast

SIMA Forecasters produce Regional SnowCasts for South Island regions when snow is forecast below 1000 metres, including alpine snow levels and impacts on mountain passes.

Weather News

Articles and updates from the SIMA Forecasters about recent and upcoming weather across the South Island.

Radar and Satellite

Live rain radar and satellite cloud imagery for the South Island, useful for tracking showers, fronts and developing storms in real time.

Independent Status and Disclaimer

South Island Met Agency is an independent private entity and is not affiliated, connected, or partnered with MetService (Meteorological Service of New Zealand Limited) or the National Emergency Management Agency (Civil Defence). SIMA does not issue official government severe weather warnings. For official New Zealand watches and warnings, visit MetService Severe Weather Warnings, and follow instructions from local Civil Defence authorities during extreme events. Full terms are available on our About Us & Terms page.

Informational Purposes Only: All content, maps, graphics, and regional forecasts provided by SIMA are intended solely for general public information. While we strive for meteorological accuracy, atmospheric modelling is inherently uncertain and subject to rapid change.

Liability Release: SIMA assumes no legal liability or responsibility for any loss, damage, disruption, or injury resulting directly or indirectly from reliance on our forecasts or publications. Always consult MetService for official emergency watches and warnings, and follow instructions from local Civil Defence authorities during extreme events.

Copyright & Attribution: All original forecast graphics, maps, and commentary generated by SIMA remain the property of South Island Met Agency unless otherwise noted.

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