Cold front

Also called cold front symbol, blue front, triangles

Weather-map symbol. A chart convention, not a forecast icon.

Cold front meaning

A cold-front symbol is a line with triangles pointing where the front is moving. NOAA lessons often draw it blue. The triangles still have to work in one ink.

At a glance

System: Synoptic chart convention
Used for: An advancing cold-air boundary
Not the same as: A warm front, or a rain icon

A line with triangles in the direction of motion. Cold air is advancing. The color is a publisher’s aid.

The name. Triangles on the side the front is moving toward. Blue is a common ink, not the definition.

Download drawing

Where it comes from

NOAA’s JetStream lesson draws a cold front as a blue line with triangles in the direction of motion. It describes that front as nearly always south or west of a low, and not as a feature leaving a high. Blue is the teaching color. A map printed in one color keeps the triangles. This drawing is gilt triangles on a line, pointing to the side of motion. It is not a claim that every publisher uses blue, and it is not a rain icon.

The line drawing is original to this cabinet. It is not an agency logo, a vendor icon, or the emoji for the same idea.

Weather

What it means

A boundary where colder air is advancing on warmer air. The triangles point into the warmer air, the way the front is moving. Weather near it depends on the storm. The symbol does not itself mean rain, snow, or thunder. Those are forecast icons or present-weather signs. The front is the boundary.

Variants

Color

Blue is NOAA’s classroom ink. Another publisher can change it. If the triangles disappear and only a color remains, the mark has been stripped. Do not rely on color alone.

Worth knowing

JetStream places a cold front nearly always south or west of a low, and not departing from a high. Source

Questions

What does a cold front symbol look like?

A line with filled triangles on the side the front is moving toward. NOAA’s JetStream lesson draws that line blue. The triangles are the part that survives in one color.

Does a cold front symbol mean it will rain?

It means a cold-air boundary is drawn there. Rain, snow, and thunder are other symbols. They may accompany the front. They are not the front.

Often confusedWarm frontWarm fronts use half-moons, not triangles. JetStream often draws those red, and usually to the east of a low.

Often confusedTroughA trough is elongated lower pressure and a wind shift. JetStream says it is not an air-mass boundary.

Near this

Sources

Named when the entry depends on a text, a date, or a standard. Catalog numbers are not invented.

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symbol.wiki, edited as Sigilla. Last reviewed 18 October 2026. A reading of public tradition, not a ruling.