A winter storm watch means hazardous conditions are possible or favorable; a warning means a significant hazard is expected, imminent or occurring; an advisory describes less severe conditions that can still disrupt travel. Exact criteria vary by local forecast office and hazard.
A watch: conditions could line up
The National Weather Service issues a watch when a significant winter event is possible and conditions are favorable. A watch is an early heads-up: the storm’s timing, track or impacts may still be uncertain. It is a cue to follow forecast updates and understand what hazards could affect the area. [1]
A warning: a significant hazard is expected
A winter storm warning means hazardous winter weather is occurring, imminent or likely enough to meet local warning criteria. The specific hazard may be heavy snow, ice, sleet or a combination. A warning calls for taking the hazard seriously and following local instructions. Criteria are adapted to regional conditions, so thresholds are not identical everywhere. [1]
An advisory: less severe, still disruptive
An advisory covers winter conditions that fall below warning criteria but can still create inconvenience or risk—such as slippery roads or reduced visibility. The NWS uses local criteria and may issue separate products for hazards such as wind chill or lake-effect snow. Read the alert text for the actual hazard, area and timing rather than relying only on its color or title.
For the physical process behind one kind of heavy snow, see lake-effect snow.
Frequently asked questions
Does a watch mean a storm is certain?
No. It means conditions could produce a significant event; confidence and timing may still change.
Is an advisory safe to ignore?
No. It indicates lower-level hazards that can still affect travel and daily activities.
Why do alert thresholds differ by place?
Local forecast offices account for regional climate, infrastructure and hazard impacts when setting criteria.
Sources and evidence
- National Weather Service — Winter Weather Warnings, Watches and Advisories ↗
Definitions and practical distinctions among watches, warnings and advisories.
- National Weather Service Boston — Product Descriptions ↗
Local criteria, warning purpose and winter product descriptions.
Sources consulted: 1 November 2026. Written with AI assistance and checked against the linked references; not independently reviewed by a subject specialist. Sources do not endorse this article. See our editorial policy.
Revision: Initial publication. Claims and uncertainty checked against the cited references.