Average First and Last Frost Dates

Links to the average first and last frost dates and growing seasons for the state of Illinois tell me that for my area, I should expect my last frost in the spring sometime between April 14th and 21st (according to the state climatologist office).  My average first fall frost is sometime between October 14th and 21st.  My growing season is somewhere between 185 and 190 days without season extension practices.

Dave's Garden has a page where I can enter in my zipcode and find out more specific information in regard to average frost dates.

The Weather Channel  page.  Again; enter in your zip code for current weather.  Then from that page, scroll down and click on the link to get your >HISTORICAL DATA.  I am seeing March 15th as our last average freeze!  It is interesting to note the difference in dates given by the various sources. I really need to buy a thermometer that saves the low and high temps and start keeping my own records.  Of course, the average is far earlier than the approximate last freeze.  One date or the other is taken into consideration depending upon what is being planted--the hardiness of the plant or lack thereof. 

On this Plant Maps page, I can really zoom in and see our area right down to the roads.

In addition to knowing the average frost dates as an aid to planning my garden, I have been interested in learning about gardening by the signs.    This is important to the philosophy of Biodynamic gardening or farming.   This goes beyond 'organic' and I like the idea of  growing our food and living in harmony with the earth.