Outflow (contrasted with inflow) may refer to:
- Capital outflow - an economic term describing capital flowing out of (or leaving) a particular economy.
- Bipolar outflow in astronomy represents two continuous flows of gas from the poles of a star.
- Discharge (hydrology) - In hydrology, the outflow or discharge of a river is the volume of water transported by it in a certain amount of time.
- Outflow (meteorology), in meteorology, is air that flows outwards from a thunderstorm.
- Outflow boundary in atmospheric science means thunderstorm-cooled air (outflow) from the surrounding air.