The formula
In dry air, c ≈ 331.3·√(1 + T/273.15) m/s with T in °C – about 0.6 m/s faster for every degree warmer. Humidity raises it slightly; air pressure alone has almost no effect.
Frequently asked questions
What is the speed of sound at 0 °C?
About 331 m/s.
What is the speed of sound at 20 °C?
About 343 m/s (1,235 km/h, 767 mph).