Several others, including myself, have remarked on "outages" in heavy cloud cover. Whether this is coincidence I have no idea.
I seem to remember reading somewhere that the power budget on the downlink can get a bit marginal, particularly to an "indoors" receiver (handheld in a closed cockpit with no external antenna), which would suggest that it wouldn't be astonishing if sufficient cloud were to tip some receivers over the edge. But you need a proper radio professional for proper advice.