I've heard this mentioned on FR today...but is there really any proof that weather drives down voter turnout in one party more than another?
In Detroit's case - the city is 93% Democrat. A big rainstorm there in 1990 was a factor in a low turnout there.
Jim Blanchard was supposed to win by at least 12% He lost by 17,000 votes to some fairly unknown state senator at the time named John Engler.