What is the difference between a weather watch and a warning?

A watch is issued when conditions are favorable for a hazard to develop over a broad area and a period of hours, and it is a signal to prepare: review your plan, know where shelter is, charge devices, secure loose objects, and stay alert to updates. A warning means the hazard is occurring, imminent, or has been detected, it covers a much smaller and more specific area, and it requires immediate action. The widely used analogy is that a watch means the ingredients are present and a warning means the cake is in the oven.

A third level fills the gap. An advisory indicates conditions that are hazardous but less severe than warning criteria, expected to cause inconvenience and possible danger if caution is not exercised, such as a winter weather advisory for a few inches of snow. The National Weather Service has been consolidating and simplifying this vocabulary over time in response to research showing that the public confuses the terms, which is a genuine public safety problem rather than a semantic one.

Practical notes worth having. A tornado warning means take shelter now in an interior room on the lowest floor, and the appropriate reaction is to move rather than to look outside for confirmation. Warnings are increasingly polygon-based rather than county-based, so alerts are targeted to the actual threat area. Wireless Emergency Alerts push the most severe warnings to phones automatically and should not be disabled, and a NOAA weather radio with battery backup remains the most reliable receiver when power and cell service fail. Finally, know that a tornado emergency is a rare escalation above a warning, used when a confirmed large and violent tornado threatens a populated area, and it means the situation is as serious as the service ever communicates.