Air Masses and Fronts
What air masses are and the weather you can expect from warm, cold, stationary and occluded fronts.
An air mass is a large body of air with fairly uniform temperature and moisture, taking on the character of the region where it formed (e.g. cold-dry continental polar, warm-moist maritime tropical). A front is the boundary where two air masses meet — and boundaries are where the weather happens.
The four fronts
- Cold front — cold air pushes under warm air. Fast-moving, narrow band of weather: towering cumulus, showers or thunderstorms, gusty wind shifts, then clearing and cooler, drier air behind.
- Warm front — warm air rides up over retreating cold air. Slow, wide area of layered cloud, steady precipitation, lowering ceilings and visibility, and a gradual warm-up after passage.
- Stationary front — neither air mass advances; prolonged clouds and precipitation over the same area.
- Occluded front — a cold front overtakes a warm front, lifting the warm air aloft; combines features of both.
Why it matters
Frontal passage brings predictable changes in wind, temperature, pressure, cloud and visibility. Knowing which front is coming — and how fast — tells you whether to expect a short, violent line (cold) or a long spell of low IFR (warm). Decode the current picture with the METAR/TAF tool.
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*Reference and training only — not for navigation. Always consult the current AIM, FAR/AIM, your aircraft’s POH/AFM, official weather products and a certificated flight instructor.*