If you have your Joomla! global configuration set up in a way that the Error Reporting is set to "Maximum" (backend Global Configuration / Server), you may see MambWeather-related notifications on your website saying that certain variables/parameters are undefined.
This is caused by weather stations not transmitting all weather data.
You can avoid these notifications by setting the Joomla! Error Reporting parameter to "System Default" or "Simple", but this is - of course - not an elegant solution.

The latest release of the MambWeather free version (v2.3.2) deals with these notifications. The MambWeather Premium and Business versions have also been updated to this extent.