मौसम किसी स्थान की अल्पकालीन वायुमंड loलीय दशाओं का द्योतक है। इस प्रकार मौसम की यह विशेषता है कि यह कभी भी स्थिर न रह कर निरंतर परिवर्तनशील एवं गतिशील रहता है।

Weather is the state of the atmosphere, describing for example the degree to which it is hot or cold, wet or dry, calm or stormy, clear or cloudy. On Earth, most weather phenomena occur in the lowest layer of the planet's atmosphere, the troposphere, just below the stratosphere. Weather refers to day-to-day temperature, precipitation, and other atmospheric conditions, whereas climate is the term for the averaging of atmospheric conditions over longer periods of time. When used without qualification, "weather" is generally understood to mean the weather of Earth.