Radar reflectivity scale

A colour ramp showing how strongly rain reflects radar.

Also known as: dBZ scale, Rain radar colours

Maps & navigationScientificStandard profile

Meanings

Weather radar images colour returns by reflectivity, in decibels. Reflectivity measures how much the radar signal is bounced back, which depends on drop size as well as on how much is falling — so hail returns strongly without meaning heavy rain.

Officially standardisedVerified fact
Colours radar returns by reflectivity in decibels, a measure of how strongly the target scatters the radar beam.
Contexts: Navigation, Maps
Officially standardisedVerified fact
Measures scattering rather than rainfall directly: large drops and hail return far more signal than the same mass of small drops, so a bright return is not simply heavy rain.
Contexts: Navigation, Maps

Visual description

A graded bar of colours running from cool to warm tones with numeric values printed alongside it.

Symmetry: none
Orientation: upright
Colours: blue, green, yellow, red

Confidence

IdentityHigh confidence: High confidence because the identity is documented in encyclopedic references, but multiple independent sources agree.
Historical originModerate confidence: Moderate confidence because the historical origin is documented in encyclopedic references, but multiple independent sources agree, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Current useHigh confidence: High confidence because the current use is documented in encyclopedic references, but multiple independent sources agree.
Visual matchHigh confidence: High confidence because the visual match is documented in encyclopedic references, but multiple independent sources agree.

Sources

Station model
Wikipedia · retrieved 2026-08-01
Tertiary reference. Used for what a symbol depicts and which authority publishes it, not for the legend of any particular chart series or the text of any standard.
Met Office guidance and warning service
Met Office · retrieved 2026-08-21
The United Kingdom's national meteorological service. Authoritative for British warnings, the shipping forecast and public presentation. Warning colour schemes are national and differ between services.
Manual on Codes and the surface synoptic station model
World Meteorological Organization · retrieved 2026-08-01
Codifies how observations are exchanged between meteorological services. Public forecast graphics are drawn with far more latitude than this allows, so it is cited for the professional convention and never for what a television weather map means.
National Weather Service
National Oceanic and Atmospheric Administration · retrieved 2026-08-21
The American national service. Cited where United States practice differs from British, which it does in warning terminology and in some chart conventions.

Last reviewed 2026-08-23

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Meteorological chart notation

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Meanings

Officially standardisedVerified fact

Colours radar returns by reflectivity in decibels, a measure of how strongly the target scatters the radar beam.

Contexts: Navigation, Maps

Officially standardisedVerified fact

Measures scattering rather than rainfall directly: large drops and hail return far more signal than the same mass of small drops, so a bright return is not simply heavy rain.

Contexts: Navigation, Maps

Confidence

IdentityHigh confidence: High confidence because the identity is documented in encyclopedic references, but multiple independent sources agree.
Historical originModerate confidence: Moderate confidence because the historical origin is documented in encyclopedic references, but multiple independent sources agree, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Current useHigh confidence: High confidence because the current use is documented in encyclopedic references, but multiple independent sources agree.
Visual matchHigh confidence: High confidence because the visual match is documented in encyclopedic references, but multiple independent sources agree.

Sources

Station model
Wikipedia · retrieved 2026-08-01
Tertiary reference. Used for what a symbol depicts and which authority publishes it, not for the legend of any particular chart series or the text of any standard.
Met Office guidance and warning service
Met Office · retrieved 2026-08-21
The United Kingdom's national meteorological service. Authoritative for British warnings, the shipping forecast and public presentation. Warning colour schemes are national and differ between services.
Manual on Codes and the surface synoptic station model
World Meteorological Organization · retrieved 2026-08-01
Codifies how observations are exchanged between meteorological services. Public forecast graphics are drawn with far more latitude than this allows, so it is cited for the professional convention and never for what a television weather map means.
National Weather Service
National Oceanic and Atmospheric Administration · retrieved 2026-08-21
The American national service. Cited where United States practice differs from British, which it does in warning terminology and in some chart conventions.

Last reviewed 2026-08-23