What Does FZ Mean in a METAR?
FZ means freezing. It stands for FreeZing.
FZ in a real report
FZRA
That reads as freezing rain.
What it changes for you
FZ is the descriptor that should stop a departure rather than adjust one.
Freezing precipitation forms clear ice on contact. That is the heaviest and most adhesive form of airframe icing, it builds fast, and it is difficult to see from the cockpit because it is transparent.
The forms and how they differ
FZRAfreezing rain, the most serious, from a warm layer aloft over a cold surfaceFZDZfreezing drizzle, smaller droplets, often in stratus with no warm layer aboveFZFGfreezing fog, supercooled droplets at the surface that ice an aircraft on the ground
All three imply a temperature inversion or a subfreezing surface. Check the temperature in the same report and the freezing level in the winds aloft.
Related codes
Decode a report containing this code
Paste a METAR, TAF, PIREP or SIGMET into the WxDecoder decoder. Every group comes back in plain English. The raw code sits beside it, so you can check the decode rather than trust it.
Frequently asked questions
What does FZ mean in a METAR?
Freezing. It is a descriptor for precipitation that freezes on contact with the surface or the airframe. FZRA is freezing rain, FZDZ is freezing drizzle, and FZFG is freezing fog.
Why is freezing rain more dangerous than snow?
Freezing rain arrives as liquid and freezes on contact, so it forms a smooth sheet of clear ice on wings and control surfaces. Snow largely blows off. Clear ice is heavy, hard to shed and hard to see.