said by SHoTTa35 :
Umm 0.0dBmV is PERFECT signal so 1.0 is worse than 0.5.
Your SNR is bad yes as you want that higher. So 35 is getting better but no idea why signals would be better but SNR gets worse. Must be some moisture or breakage on the line and the higher input power overpowers the noise caused by the leak?
I wonder if some amp is somewhat weak as it gets cold and keeps trying to push it's gain up, causing the extra noise despite the slightly weaker signal.