When reading a METAR, what does "NSW" stand for?

In the context of interpreting a METAR report, the abbreviation "NSW" stands for "No significant weather." This term is used to indicate the absence of significant weather phenomena that would impact visibility, flight operations, or other meteorological observations.

When "NSW" appears in a METAR, it communicates to the reader that there are no weather conditions such as rain, snow, fog, or thunderstorms that would warrant special attention. This is useful information for pilots, air traffic controllers, and meteorologists as it helps them understand that the weather is relatively stable without notable atmospheric disturbances at the time of the observation.

Understanding this term is crucial because it allows weather observers and users of METAR reports to quickly assess that the current weather does not present any significant operational concerns.