Possible Clues:

• To smell, I had to get close
• Quite moist
• Describes air with a great deal of water vapour
• Rather wet philosopher failing to finish papers
• One of the three H’s
• (Of atmosphere) with high water vapour content
• Sticky, in summer
• Close concealed bags I'm thinking
• Moist, warm (weather)
• Sing under by breath, so I would, when it's so hot