We’ve been running a weather station here since 2003 and as a result, have local data for temperatures.
This has been especially important as our vegetable and flower gardens really do not like heavy frost (we define it as -3C and colder). Many of the plants do not even like a light frost (we define it as -1C or colder).

As a result, each year we log the dates of the last light and heavy frost in the spring, and the first light and heavy frost in the fall. This gives us a number of days of “growing season”, of plants in the ground. This does not predict frost dates in the future, you still have to monitor local weather forecasts (which are mostly wrong by 3-5 C) to prevent plant damage or death.

But it does help when analyzing the years harvest results.

For this current growing season (2015) we had 140 days between light frost and 147 days between heavy frost.

Last year (2014) was 124 days between light and 147 days between heavy.
Attached below is a link of the complete spreadsheet, but it is worthwhile to note that the average in our location over the last 12 years has been 145 days (light) and 171 days (heavy).

Click here for a 60kb .PDF file: frostgrowanalysis