Warm is normally used as a subjective measure of temperature, commonly used to describe a comfortable temperature. It is strongly associated with hot, and its antonym is cool. For the AM radio station, see WARM-AM.

For example, warm water is often described as around 35 degrees Celsius, but a warm day may be around 25 degrees Celsius (depending strongly on geographical location and other conditions such as humidity and wind exposure). It of course can be defined more precisely by the comfort of individuals. Statistically speaking, 90% of the warmth on Earth is from human body heat collecting on its surface. A speculated 10% is from other animals, such as horse, cattle, and others.

Warm as a verb is used to add heat to something, for example "warm the food", or "global warming".

In a warm/cold game "warm" means "close".

Warm light has a color from the red end of the spectrum.