illustration of a girl in purple holding a warm yellow ball of glowling light with a dialogue balloon asking 'is it warm or cool?'

Colour Vocabulary – Temperature

Here is another often used term you may come across in Colour theory posts – ‘Colour Temperature’ or ‘Warm’ and ‘Cool’ colours.

You can read the previous post on common colour related terminology here!

What is colour temperature?

Temperature refers to the warmth or coolness of a colour. This temperature affects the perception we have about these colours, especially in the depth, and mood.

Have you ever noticed that far-away mountains tend to look blue? Think of it this way, those far-away mountains look that far-away because they are blue!

The reason they appear blue is atmospheric. But that blueness makes them appear even farther away in depth is a play of that colour. Cool colours tend to recede from our eye.

In contrast, warm colours appear to advance or come closer.

The technical reason is that the wavelengths of warm colours are longer hence they reach our eyes sooner than the wavelengths of cooler colours.

I’ll take you back to Newton’s colour spectrum for an instant.

circle in black and white describing the way newton saw the visible colour spctrum and laid out in a circular wheel.

The spectrum of colours appears the way it does because of the different wavelengths of each colour. So, if we followed the spectrum, we could observe the longer wavelengths (Red side) and the shorter wavelengths (Violet side).

This already hints that, certain colours are cool and certain colours are warm, based on their wavelengths. The yellow-red-orange is warmer and the blue-purples are cooler.

But temperature is not purely defined by that wavelength. It is relative. A colour might appear cooler just because it is placed next to a warmed colour, due to contrast. That also means every colour could tend towards warm or cool!

This brings us back to the term Hue. Hue refers to an entire colour family. So when I say blue hue, it says nothing about the temperature of that colour. But we know there are many versions of blue. Like these blue marbles![/vc_column_text]

series of marbles in various shades of blue with some greens
Image by Tanakawho from Flickr

So I could say there are warm and cool versions of practically every colour.

Looking at our CMY colour wheel with this lens of temperature, I can classify the warm and cool sections thus.

Warm colours
Warm Colours
colour wheel in watercolour showing only cool colours
Cool colours

Warmth and coolness thus also have an impact on mixing colours

From the wheels above one can observe warm colours tend towards yellow and oranges and reds. So If I had to ‘warm up’ a colour, I could add one of these, or select colours towards the warmer side of the wheel.

Cyan, turquoise, and purple tend to be cooler. So I could cool something down by moving towards the cooler side of the colour wheel.

Transitioning from warm to cool
Transition of colour temperature across the colour wheel

If we mix colours that tend toward the same temperature, they will form a harmonious and brighter mix.

This is one of the reasons for the CMY wheel to produce such a bright and vibrant range of colours. Both the cyan and magenta are on the cooler side and only yellow, which can be neutral to warm, brings in the warmth to the mixes.

When we mix warm and cool colours together we inevitably get some desaturation or dullness.

Think about why that might happen.

For example- Cyan (a cool blue) can mix a brilliant purple with magenta but a duller mix with a red.

Why? Because red is warmer than magenta. That is also because it has some yellow in it, which is the colour on the opposite of purple, hence it’s complement. So, by mixing Cyan with Red, we are mixing in Cyan + Magenta + Yellow. The yellow content is not enough to neutralize the mix to black, but sufficient to dull or muddy it down!

Did that make sense?

This is one of the most common reasons for colour mixes to turn ‘dirty’ or ‘muddy’.

Warm and Cool versions of colours

What does that mean? How can there be cool red or warm blue?

Since our pigment colours are not the exact representative of the light spectrum, we have a large variety of hues to choose from.

If you recall the CMY primaries, the cyan is an intense and cool blue, magenta is an intense and cool red.

If I look at the RYB primaries, I can clearly find the absence of cool reds, which is the primary reason that that combination fails as primaries!

In Yellows, cool yellows tend toward greenish and warm ones toward red or orange.

In Blues, cool blues also tend toward greenish and warm ones toward the red (becoming purpleish)

In Reds, cool reds tend toward blue (becoming pinkish or magenta) and warm reds tend toward orange/yellow.

In my observation, I’ve also found that it is possible to ‘warm up’ a colour by bringing in the yellows, but not possible to cool a warm colour down as that inevitably results in dirty mixes. This is another reason the CMY wheel works. It is primarily a cool colour base wheel which has a yellow to warm up the hues as needed.

Here are some commonly found watercolour swatches and a loose classification of whether they are warm or cool. In many cases, it is difficult to define warm or cool without comparing with some other colour. Temperature is very relative. We can try to place the hue on the colour wheel in our mind, to figure out if it tends towards the red/orange side or blue/cyan side.

These are some warm and cool versions of common watercolour pigments. Do note that the colour will not be 100% accurate to the paint as I have scanned these swatches. I have tried to make it appear closest to its real appearance but display and colour gamut will vary across devices causing it to appear a tad different to different viewers.

Here are some common Yellows:

Warm Yellows

watercolour swatch of Sennelier Yellow lake

Yellow Lake – Sennelier

It appears warm when compared to a cool yellow, but otherwise close to neutral

This is being used as the primary Yellow in the CMY wheel.

watercolour swatch of Sennelier Cadmium Yellow Deep

Cadmium Yellow Deep – Sennelier

An obviously warm yellow, almost orange.

Cool Yellows

watercolour swatch of Sennelier Lemon Yellow

Lemon Yellow – Sennelier

A cool and bright yellow

Warm and Cool Reds- Yes there can be coolness in Reds, which tends towards magentas and pinks!

Warm Reds – these range from deep oranges to bright typical reds.

watercolour swatch of Sennelier Bright Red

Bright Red – Sennelier

A classic red colour, has a bit of yellow to it.

watercolour swatch of Sennelier French Vermillion

French Vermillion – Sennelier

A warmer red, tending towards orange but not quite.

Cool Reds

watercolour swatch of Sennelier Carmine

Carmine – Sennelier

Cool but still reddish

watercolour swatch of Winsor & Newton Permanent Rose

Permanent Rose – Winsor & Newton

Also known as Quinacridone Rose, cool but not too magenta-ish

watercolour swatch of Sennelier Helios Purple

Helios Purple – Sennelier

Very strong Pinkish hue- my choice for the Magenta of a CMY wheel

Warm and Cool Blues

watercolour swatch of Mijello Mission Gold Cobalt Blue No.2

Cobalt Blue No.2 – Mijello Mission Gold

This is a close-to neutral blue hue

watercolour swatch of Sennelier Ultramarine Blue Deep

Ultramarine Blue Deep – Sennelier

A strong and red-toned blue, most common warm blue in many palettes

watercolour swatch of Sennelier Phthalo Blue Red shade

Phthalo Blue Red Shade – Sennelier

A strong pigment which comes in 2 variations, one reddish and one greenish.

watercolour swatch of Sennelier Phthalo blue green shade

Phthalo Blue Green Shade – Sennelier

A strong and highly pigmented colour, with a greenish bias. This is what I use as the Cyan in the CMY wheel.

watercolour swatch of Daniel Smith Cerulean Blue Chromium

Cerulean Blue Chromium – Daniel Smith

A soft and granulating but cool hue

Were you surprised to see that reds have cool versions and blues have warmer versions?

This gives us a possibility for each secondary colour to be a derivative of cool/warm combination of its primaries!

Each set of colours have an advantage to bring. For example, Cool yellows mix to clear and vibrant greens with cool blues, as seen in the CMY wheel. Making one of the colours warm, either the blue or the yellow, can get a more natural range of earthy or mossy greens.

swatches of mixing warm blue with cool yellow and warm yellow

Warm blues and warm reds make the warmest dull purples while cool blues and cool reds make deep stormy violets.

This is because warm red has a tinge of yellow – so when mixed with blue for purple, mixes with blue to make green. Green is the opposite of red on the colour wheel and neutralizes or ‘muddies’ the mix a bit.

When both the hues are cool, the blue has a tinge of green in it.

Thus the purest mix of purple comes from the warm blue and the cool red.

This is because Cool red has a tinge of blue (coolness) and warm blue has a tinge of red (warmth) in it, hence the combination of the cool red and warm blue is essentially a mix of only red and blue.

swatches of mixing warm and cool blues with warm and cool reds

This leads to one of the artist’s primary tools in being able to depict all colours in nature easily without too much mixing – the split primary colour palette.

Instead of trying to find the perfect CMY primaries which can mix all the colours, we take the simpler route, reduce our mixing effort, and choose two sets of primaries, one warm and one cool.

A warm blue and a cool blue, a warm red and a cool red, a warm yellow and a cool yellow.

Artists have been using this tool for years, mainly because the traditional RYB (Red Yellow Blue) primaries were not enough to mix all the colours they wanted. But even with our new knowledge of the CMY primaries, adding multiple versions of the primaries can help reduce the amount of mixing required and add some convenience to the palette.

I will explore how we can introduce some more colours to our CMY primaries to make a well-rounded palette in the next post.

How to use ‘colour temperature’ in practical life?

Understanding the warmth or coolness of a particular paint helps us get vibrant mixes, or neutral mixes as we want.

Warm and cool colours can be used in the composition to play up contrast and dynamism to lead the eye to the focal point.

Colour temperature plays a huge role in setting the mood of a scene. Just imagine how dreary and depressing cool white office lights feel compared to a cosy warm restaurant or candlelight setting! We can achieve create similar impact on a viewer’s mood with our use of warm and cool colours.


This post is part 4 of a 5-part series on colour theory and the basics of the colour wheel. The others in the series are linked below.

1 Primary Colours?

2. Colour Vocabulary – Hue, Value and Saturation

3. The CMY Colour Wheel

4. Colour Temperature  (this one)

5. Expanding the CMY colour wheel



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