A wise person, eager to sell outdoor gear, once told me, "There is no bad weather, only inappropriate clothing." When it comes to day hikes in the rain, I'd have to agree.
If I'm just out for an hour or two, I love hiking in a light rain. I love how the smells come out of the earth and the trees, and I like the muffled sounds and the atmosphere of gray and dark. The appropriate clothing is a decent rainjacket that keeps the bulk of the rain off of you, and some fleece underneath the jacket and maybe a warm cap. With that clothing, I'm in great shape and the weather is just fine. Keep moving, stay warm, take it all in.
Hiking is not fun in a seek-shelter downpour, of course, though those minutes tucked under the spruce tree boughs or inside the old barn waiting for the heaviest rain to pass are memorable. I enjoy the kind of rain where you might even leave your hood down for a while. That frees up my ears to hear the sounds, undisturbed by the rustle of the nylon hood on my earlobes.
No place is more moody than the dunes and barrens at the end of Minnesota Point, on the far extension of Duluth. Pictured above is the Superior Entry, reached after 2.5 miles through the old-growth pines, past the ruined lighthouse, and across the barrens that practically shout "Heathcliff!"
Big bonus to hiking in the rain, especially if you tend toward the romantic (that's Romantic, like the Bronte sisters) or despondent: you have the trails to yourself.