LED Legend

This is the most favorable condition for pilots.  VFR allows all aircraft and certified pilots to fly.  The clouds, visibility, and general weather conditions are favorable for flight.

Technical conditions:

Ceiling >3000 ft and Visibility >5 miles.  Sky clear.

IFR indicates that the airport is observing Instrument Meteorological Conditions, which essentially mean that the pilot and his/her aircraft must be capable of flying solely by their onboard instrumentation.

Technical conditions:

Ceiling 500-1000 ft and/or Visibility 1-3 miles.

If an airport has winds (gusting or sustained) of more than 25 knots, the airport's LED will fade/blend yellow to whatever flight category the airport is currently observing.

This weather condition is, for the most part, still fine for most pilots to fly in, but they may have to dodge some clouds along the way, and could be indicative of inclement weather nearby.

Technical conditions:

Ceiling 1000-3000 ft and/or Visibility 1-3 miles.

LIFR is usually the type of weather that includes such poor visibility, you don't want to drive in (let alone fly).  Pilots and their aircraft must be equipped with the appropriate instrumentation, and be ready to divert to another airport if conditions are bad enough.

Technical conditions:

Ceiling <500 ft and/or Visibility <1 mile.

If an airport has observed lightning in the vicinity, the airport's LED will flash white, then back to its observed flight category.