Understand weather alerts and the systems behind them
Explore practical guides to weather warnings, alert maps, severity, global warning systems, marine information, data freshness and how AlertWatch World presents official information.
UNDERSTANDING ALERTS
Weather Alerts Explained: Warnings, Watches, Advisories and Statements
Understand what common alert terms generally mean, why they differ between agencies and countries, and why the full official message matters more than the title alone.
Weather Alert Severity Explained: Extreme, Severe, Moderate, Minor and Unknown
Learn how AlertWatch World uses a common five-level severity display, why severity is separate from urgency and certainty, and why Unknown does not mean harmless or low risk.
Why Weather Alert Counts Differ Between Countries
See why raw alert totals cannot be treated as country danger rankings, and how geography, update practices, languages, marine products and source coverage affect record counts.
MAPS & DATA
How to Read a Weather Alert Map
Learn what polygons, points, colours and boundaries mean on an alert map—and why a warning shape is not necessarily the exact physical footprint of the hazard.
What Does “Data Stale” Mean on a Weather Alert Website?
Understand publication freshness, how it differs from the age of individual warnings, why last-good data may be retained, and what to do when AlertWatch marks data stale.
Why a Weather Alert May Still Appear After Its Expiry Time
Learn why expiry, event-ending time, update and cancellation are different concepts, and why international warning lifecycles cannot always be handled with one universal rule.
GLOBAL WARNING SYSTEMS
How Weather Warning Systems Differ Around the World
Explore why warning terminology, thresholds, colours, geography and lead times differ among national meteorological services, and how CAP helps different systems exchange alert information.
NWS, ECCC and WMO/SWIC: How the Warning Sources Fit Together
See why AlertWatch World combines direct U.S. and Canadian pipelines with WMO/SWIC international records instead of relying on a single source for every country.
What “Worldwide Weather Alert Coverage” Really Means
Understand what AlertWatch’s Worldwide dataset includes, why worldwide reach does not mean universal completeness, and why a blank area on the map does not prove that no warning exists.
SPECIALIZED & PRACTICAL GUIDES
Understanding Marine Weather Warnings
Learn how marine warning systems differ from land alerts, why marine geography can be complex, and why some marine records are intentionally shown with Unknown severity.
Waterspout Alerts: Watches, Warnings and What They Mean
Understand how Canada and the United States currently communicate waterspout risk, why a waterspout-related alert may not be titled “Waterspout Warning,” and why AlertWatch classifies these records conservatively.
How to Use AlertWatch World During Severe Weather
Use AlertWatch as a situational-awareness tool: check freshness, inspect the map, read the alert, identify the issuing authority and follow official instructions when conditions affect you.