Yay, I think I have what you need! This was posted in another forum, but think it's incredibly useful.

http://www.erh.noaa.gov/box/dailystns.shtml

Thanks. I've looked there before and have not found any historical frost data. Please let me know if I'm missing it though.

Not quite sure what you're looking for. Khabibul's link provides the lowest temp for each day in the MnT column. You want before 1997?

Maybe your county Extension Service could help? Weather records often taken at nearest airport?

Not precisely what you're after, but there's a link at www.weather.com for "Historical Monthly Averages", click on month for "Daily Averages". When you enter your zip code, tells you date and year for lowest (and highest) temp for that month in your zip, data goes back further, at least 1940s.

Try:
http://www.weather.com/outlook/homeandgarden/garden/climatology/monthly/12345
replacing 12345 with your zip code.

Thanks for posting the link. I am looking for the actual first and last historical frost dates. Not the averages....not high and low temperatures, but I guess if I come up with nothing I could use the actual low temp data. I just find it hard to believe that this info does not exist on the net somewhere.

I've tried looking for historical winter lows on the web. If the information is there, it's very hard to find. I would think historical frost dates would be the same thing.