In August near the Nantahala I had to use a Wilderness Logic's Slug Tube during the day because it's ALWAYS foggy there. It really helped keep everything from feeling damp. That weekend I killed a watch on the river, nearly killed my phone by just having it in my hammock over night and even my WP camera got some moisture in it! The issue there is the combination of warm air and frigid water from the dammed controlled river that is deep down in a gorge and sees little sun. But my down was golden thanks to Marty!