Persistent high pressure over the state of Wisconsin has led to a dry period through the first half of October.
Through the 15th, Milwaukee has seen only 0.04" of rain for the month, and Madison has recorded 0.02". For Milwaukee, this value ties for 6th driest all time, and Madison is the 7th driest. Average precipitation for this time period is 1.14" for Milwaukee and 1.00" for Madison
Going back a little farther, the end of September was also very dry in southern Wisconsin. The last 7 days of the month recorded only 0.01" of rain in Milwaukee, and 0.12" in Madison. If we look at the entire 24 day period from September 22 through Oct 15, 2010, Milwaukee has recieved only 0.05" of rain, making it the driest on record for that time period. Madison ranks 3rd with 0.14" of rain (the driest year was 1876 with only 0.03").
It has also been a warm start to the month, but a brief cool period Oct 2-4 keeps both cities out of the top 15 warmest starts to October.