An anti-clockwise shift in wind direction in the Northern Hemisphere, often indicating the approach of a low pressure system or cold front.
Backing is an anti-clockwise change in wind direction in the Northern Hemisphere — for example, a wind shifting from westerly through southerly to south-easterly. It is the opposite of veering. In the Southern Hemisphere the convention is reversed. Bowditch (American Practical Navigator) associates backing winds with the approach of a depression or an advancing cold front, typically accompanied by falling barometric pressure and increasing cloud cover.
For a navigator, a backing wind is an early warning signal of deteriorating weather. A vessel experiencing a backing south-westerly wind, combined with a falling barometer and thickening cloud, is likely positioned ahead of an approaching frontal system. Recognising this pattern in time allows the master to implement heavy-weather preparations — securing deck cargo, checking lashings, adjusting course or speed — before conditions worsen.
The distinction between veering and backing is also important when monitoring wind shifts in the context of tropical revolving storms. In the Northern Hemisphere, a backing wind experienced by a vessel suggests it may be positioned on the left side of the storm track — the navigably safe semi-circle — whereas a veering wind indicates the more dangerous right-forward sector. Officers should cross-reference wind direction changes with barometric pressure trends and the latest available storm warnings when operating in tropical regions.