Translation guide
How to express that something becomes red in Japanese, depending on what is turning red and why.
Something changes color to red.
The most common and neutral way to say something turns red. Works for objects, lights, leaves, etc.
The traffic light turned red.
The leaves turn red.
A literary or poetic verb meaning 'to become red' or 'to redden', often used for the sky or leaves.
The sky turns red.
A person's face turns red from embarrassment, shyness, or anger.
Eyes become red from crying, lack of sleep, or anger.
A traffic signal changes to red.
Leaves change color to red in autumn.
Metal turns red from heat.
赤くなる is the default for 'turn red'. 赤む is rare and literary. 赤面する is specifically for blushing (face).
His face turned red with anger.
She blushed and looked down.
In formal or written contexts, 赤面する is preferred over 顔が赤くなる for blushing. 顔が赤くなる is more colloquial.
She laughed, her face turning red.
The light turned red at the intersection.