771 error message but only when the outside temp drops below 40 degrees

Every year for the last three years I get a 771 error message but only when the outside temp drop below 40 and it is frustrating I believe it's the lnb more than likely,I do still get some channels but lose a lot of hd channels and some sd channels and once more I will say it's only when outside temp goes below 40 which where I live is every night into the morning our and when the sun comes up and is out this time of year they come back on so I'm about over this problem