the graphic tab doesn't refresh; but the values in the WeatherWatcher driver main tab are regularly updated?
if this is the case I would say is an issue of communication between the driver and the weather tab else it is the driver that fails reading the data from file.
To rule out any data format issue, can you try using the exact format provided in the driver manual (e.g. safe as numeric)? dataGMTTime=2019/03/16 13:13:40 clouds=-11.430000 temp=27.810000 wind=4 rain=2432 light=0 switch=0 safe=0
If this doesn't help, sending the log file could help to understand the cause.
Ferrante