Now that we've had our first light frost, I can pull out the old "autumn weather updates" template:
First light frost of autumn: 2009 September 20
First hard frost of autumn: 2009 ???
By the way, did I mention that we've had about a quarter of an inch (about 6 mm) of rainfall in September, which is less than 008% of average? Our well water, for the first time since we've lived here, smells like sulphur. Seven out of eight VERY dry months are finally catching up to us...