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 (2016) we had 130 days between light frost and 138 days between heavy frost.
Last year (2015) was 140 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 13 years has been 144 days (light) and 168 days (heavy) and is trending down.
Time for between heavy frosts (-3C)
Year weeks days
2003 28 198
2004 29 201
2005 32 222
2006 no data no data
2007 22 153
2008 23 160
2009 26 179
2010 20 143
2011 24 167
2012 24 165
2013 24 168
2014 21 147
2015 21 147
2016 20 138
If you think this means global climate change is bogus.. you are so wrong.. I laugh in your general direction.
Global warming means there is more energy in the system. Ever looked at a bell curve distribution of water temperature as you bring it to a boil? It takes energy to boil, initiate a phase change from liquid to vapour, and only a small percentage on the right side is at the boiling point/phase change. The whole pot of water may be at 100C but it does not all flash over into steam all at once does it?
What happens when you add more energy into the system? The whole curve shifts a little to the right. And what happens to the area under the curve at the right side where the boiling point liquid/vapour phase change is going on? It gets a lot bigger. This tells you that even small amounts of shift can cause much larger changes at either end of the curve.
How does this relate to weather and climate change? The more energy in the system the more variable the weather. The more extreme events (on either end) we get.
A closer look at the weather station data shows that the diminishing growing season is solely the result of singular events late in the spring or early in the fall. In the past, once -3C hit in the fall, it almost always stayed there. In the spring, when it last happened, it would tend to stay cool as well. Last year (2015) we got hit with a late May -6C that killed most things above ground. That was very abnormal.
Get used to more abnormalities.
We can get around them by better protecting the gardens against these anomalous events… covering them up using row cover, or mini greenhouses, or hoop houses, etc.