What is indicated by the term "frq" in the METAR report for lightning?

The term "frq" in a METAR report indicates "frequent" lightning activity. This term is used to describe the intensity and frequency of lightning occurrences during the observation period. When "frq" is reported, it means that lightning is occurring often enough to warrant such a description, which can significantly impact flight operations and safety.

In contrast, other terms like "ocnl" (occasional), "cont" (continuous), and "isol" (isolated) provide different nuances of lightning occurrence, but "frq" specifically denotes that the lightning is happening regularly, thereby alerting pilots and weather observers to take necessary precautions. This understanding is crucial for interpreting weather reports accurately, especially when assessing the potential risks associated with frequent lightning during flight.