Final answer:
The best option if you need to leave the frequency on an airplane to update the weather is to hold a conversation with air traffic control on another frequency.
Step-by-step explanation:
If you only have one radio on the airplane and need to leave the frequency for a few minutes to update the weather, the best option would be to hold a conversation with the air traffic control (ATC) on another frequency. ATC will guide you through the process and ensure the safety of your flight while you update the weather information. This is a standard procedure in aviation to maintain communication and safety during flights.