Now, think about what changes, in the data you want to send, at what frequency. The sensor readings probably change quite often. Tomorrow's forecast? Not so often.
So, think about sending one small message with the stuff that changes often, another message with the stuff that might change hourly, another with the stuff that changes only twice a day.
Include in the message a string that defines what kind of packet it is, so the parser can put the parsed data in the appropriate places.