Open any rain radar and you will see the same thing: patches of green, yellow, orange, and red drifting across the map. Those colours are not decoration — they are a precise scale of rain intensity. Once you can read them, a single glance tells you whether to expect a drizzle you can ignore or a downpour worth waiting out.
Overview
Radar colours represent reflectivity — how much of the radar’s signal bounced back from precipitation, measured in dBZ (decibels of Z). Light rain returns a weak echo, heavy rain a strong one. The map converts those values into a colour ramp that runs from cool colours (light precipitation) to warm colours (intense precipitation). If you want the physics behind the scale, see our deep dive into radar reflectivity (dBZ).
What Each Color Means
Light blue / light green — drizzle and very light rain
Roughly 5–25 dBZ. Barely wetting the pavement; often you can walk through it without an umbrella. At long range this can also be light snow.
Green — light to moderate rain
Roughly 25–35 dBZ. Steady rain that soaks you within minutes. The most common colour on the map in temperate climates.
Yellow — moderate to heavy rain
Roughly 35–45 dBZ. Rain hard enough to reduce visibility on the road and overwhelm light clothing. Often marks the core of an ordinary shower.
Orange — heavy rain
Roughly 45–50 dBZ. Downpour territory: gutters overflow, driving requires slower speeds. Frequently associated with thunderstorms.
Red — very heavy rain, possible small hail
Roughly 50–60 dBZ. Intense rainfall rates, flash-flooding potential, and active thunderstorm cores. If a red cell is heading toward you, get indoors.
Purple / magenta — extreme precipitation and hail
Above about 60 dBZ. Echoes this strong are usually large hail or torrential tropical rain. Purple cores are the most dangerous part of any storm on the map.
Why Colors Differ Between Apps
There is no single official colour standard. Different services cut the dBZ scale at different points, and some add colours for snow (often blue) or freezing rain (often pink). The intensity legend on the RainyMap live map always shows the exact scale in use, so check it rather than assuming colours match another app. The physics underneath — explained in How Does Rain Radar Work? — is identical everywhere.
Frequently Asked Questions
What does purple mean on a rain radar?
Purple or magenta marks the strongest echoes on the scale, typically above 60 dBZ — usually large hail or extreme, tropical-style rainfall. It is the colour to take most seriously.
Is green on the radar anything to worry about?
No. Green indicates light to moderate rain. You may want an umbrella, but it poses no hazard. Watch instead for yellow and orange cores embedded in a green area, which show where the rain is intensifying.
Why does the radar show colour over my area when nothing is falling?
Weak echoes (light blue and light green) sometimes come from rain that evaporates before reaching the ground, or from non-weather targets like birds and dust. The lighter the colour, the less certain the rain.
Do the same colors mean the same thing for snow?
Snow reflects more weakly than rain, so even heavy snow rarely climbs above the green–yellow range. Some maps switch to a dedicated blue scale when precipitation is falling as snow.