MetService warning vs watch: what's the difference?
Watch means “be ready,” Warning means “take action.” Here's how MetService's three-step severe weather system works and what each colour is telling you to do.
A MetService Watch means severe weather is possible and you should be prepared; a Warning means severe weather is expected and you should take action. The Watch is the earlier, less certain alert — typically issued two to three days ahead when an event looks likely but its exact area and severity are still being assessed. A Warning follows, usually around 24 hours out, once forecasters are confident the weather will exceed MetService's severe weather criteria.
The three-step system: outlook, watch, warning
MetService uses a graduated “1-2-3” structure that escalates as an event becomes clearer and closer.
- Severe Weather Outlook — the earliest heads-up, covering weather that may occur three to six days ahead. It marks regions where rain, snow or wind could reach warning criteria, each tagged with a confidence level of minimal, low, moderate or high.
- Severe Weather Watch — issued when severe weather is likely to require a Warning, but the affected area and exact severity are still under assessment. Think of it as “be alert and get ready.”
- Severe Weather Warning — issued when forecasters have high confidence the weather will meet or exceed severe criteria, usually about 24 hours out. This is “take action now.”
| Alert | Lead time | Certainty | What to do |
|---|---|---|---|
| Outlook | 3–6 days | Possible | Stay aware; check for updates |
| Watch | 2–3 days | Likely | Prepare; plan around it |
| Warning | ~24 hours | Expected | Take action to protect people and property |
What do the orange and red colours mean?
Warnings come in two colours that signal impact and urgency. An Orange Warning means take action: incoming heavy rain, strong wind or heavy snow is expected to meet severe weather criteria and disrupt daily life. A Red Warning is reserved for only the most extreme events — the kind of heavy rain, damaging wind or heavy snow associated with, for example, an ex-tropical cyclone — that are likely to cause significant impact and disruption. Red means act now: follow the advice of authorities and Civil Defence, and don't travel into the affected area unless you must. The February 2023 ex-tropical Cyclone Gabrielle, which drew Red Warnings across parts of the North Island, is a stark example of when that top tier is used.
What counts as “severe weather”?
MetService applies specific thresholds so warnings mean something consistent. “Severe weather” covers heavy rain, heavy snow, strong (gale) winds and thunderstorms, each with defined criteria. For thunderstorms, for instance, heavy rain is defined as falling at 25 millimetres per hour or more. “Widespread” in the criteria means an area of at least 1,000 square kilometres. Thresholds also account for terrain and region — the rainfall total that threatens flooding on the flat differs from what the steep, saturated ranges can absorb. The exact figures are published in MetService's severe weather criteria, and it's the crossing of these thresholds, not just “bad weather,” that triggers a Watch or Warning.
Why does a Watch sometimes not become a Warning?
Because the atmosphere is uncertain, and MetService would rather give you early notice than a late one. A Watch is issued when an event looks likely; as newer data arrives, the system may weaken, shift offshore or track somewhere else, and the Watch is stood down without a Warning. That's the system working as intended — not a false alarm. It's also why watching the trend matters: comparing successive forecasts tells you whether the threat is firming up or fading.
How does model agreement relate to watches and warnings?
Forecasters lean on multiple numerical models when deciding whether to escalate. When the European ECMWF, American NOAA GFS and German DWD ICON models agree that a system will hit hard, confidence is high and a Watch can move to a Warning quickly. When they diverge on track or intensity, uncertainty is greater and an alert may sit at Watch longer. checkweather.io makes that agreement visible: it compares the three global models side by side, distils their consensus into a plain-English confidence score, and grades an accuracy scoreboard after the fact — no black boxes. It's a useful companion to the official picture, and it always links through to MetService, the national authority whose Watches and Warnings are the ones to act on.
How do warnings reach you, and how often are they updated?
MetService issues its Watches and Warnings through its website and app, and feeds them into the national emergency alerting system so that Civil Defence and the media can amplify them. Warnings are reviewed and reissued as an event evolves — an Orange Warning can be upgraded to Red if the situation worsens, extended to cover new areas, or lifted once the threat passes. Because of this, a warning is a living product, not a one-off notice: the version you saw yesterday may have changed by this morning. During a major event it pays to recheck regularly rather than assume the first alert is the final word, and to note the specific areas and time windows each warning covers, since a single system can carry different colours for different regions at once.
What should I actually do for each?
For an Outlook, simply stay aware and keep checking. For a Watch, prepare: secure loose items, plan travel around the likely timing, and think through your options if conditions worsen. For an Orange Warning, act to protect people and property and avoid unnecessary travel in the affected area. For a Red Warning, treat it as an emergency: follow official instructions, stay off the roads, and be ready to move if told to. The colour and the word together tell you both how bad it will be and how soon.