METAR weather code reference for FZ (Freezing)
Indicates that liquid precipitation is freezing upon contact with surfaces at or below 0 degrees Celsius. Freezing rain (FZRA) and freezing drizzle (FZDZ) are among the most dangerous weather conditions for aircraft, causing rapid ice accumulation on wings, control surfaces, and engine inlets. Freezing fog (FZFG) deposits rime ice on exposed surfaces.
Here are common ways FZ appears in real METAR observations:
FZRAFZDZFZFGThese METAR codes are commonly seen alongside FZ or describe related weather phenomena:
Liquid precipitation in the form of water droplets greater than 0.5 mm in diameter. Rain is the most commonly reported precipitation type in METARs and can be combined with intensity modifiers (- for light, + for heavy) and descriptors like SH (showers) or FZ (freezing).
Very fine, uniformly dispersed liquid precipitation with droplets smaller than 0.5 mm in diameter. Drizzle typically falls from stratus clouds and indicates stable atmospheric conditions with low ceilings. Freezing drizzle (FZDZ) is especially hazardous for aircraft.
A visible aggregate of microscopic water droplets suspended at the earth's surface that reduces visibility to less than 5/8 of a statute mile. Fog is one of the most common causes of IFR conditions and flight delays. When visibility improves above 5/8 mile, the observation changes from FG to BR (mist).
Also known as diamond dust, ice crystals are tiny, unbranched ice particles that fall from a clear or nearly clear sky. They are most common at very cold temperatures (below -30C) and can create optical phenomena like sun dogs and halos. Often observed at high-altitude airports in arctic regions.