Provided you have a 'Pilot Flame' type.....
Thermocouple 'PROVES' pilot flame is lit by generating milivolt signal (12 milivots or higher) to keep magnet latched allowing gas to flow to pilot.
Thermocouple getting shorted out due to rain...signal drops out ....magnet closes....pilot flame goes out
Now IF you have a Gas Only DSI type...
Then rain is getting on the ECO (red wires) and shorting out the 12V DC going to gas valve causing to close
OR
Rain is getting on wire from circuit board to spark electrode shorting it out causing 'PROVE' signal to drop out....circuit board shuts down gas valve
What is your MODEL NUMBER??????????
Is it time for your medication or mine?
2007 DODGE 3500 QC SRW 5.9L CTD In-Bed 'quiet gen'
2007 HitchHiker II 32.5 UKTG 2000W Xantex Inverter
US NAVY------USS Decatur DDG31