I have successfully installed the plugin on 2 separate Polisys, using 2 different Weatherbit API's (2 accounts).  The data fields seem to populate OK but on 1 Polisy, I get a 429 error.  Any suggestions?

I believe the 429 error is because you've exceeded the number of calls you're allowed to make (in a day, if I recall correctly). 

You may need to increase the polling interval.

OK.  It is strange that only one policy gets the error and the Weatherbit plugins are set up on 2 separate accounts.

The error is coming from WeatherBit

https://help.weatherbit.io/faq/what-happens-when-i-exceed-a-rate-limit/

Understood, but why would one plugin have an error and the other does not (given the polling settings are the same but the API's differ)?

I don't know and I have no way to investigate that.  From the information about the WeatherBit API, the number of queries made by the plug-in are the only thing that should trigger that and the polling setting is the only configuration of the plug-in that controls the number of queries it makes.

Makes sense. I have the free “hobby” subscription so any recommendations on the polling settings?

So I have the short poll set at 3700 and long poll at 43200 but still get the 429 error