The correlation between weather factors and background radiation levels have been investigated in an experiment that took place in Australia.
David put together one uRADMonitor unit and a weather station, and aligned the output data using a python script.
As David explains:
"I’ve been running uRAD unit #12000003 here in Australia for around 12 months now and the only time I’ve really seen a solid increase in readings is during heavy rain which got me thinking, what other weather conditions affect radiation levels?"
See the tools he used and more details on Weather vs Radiation readings