In my last blog, I looked at how much annual rainfall in gardens varies (and hence what our plants and wildlife have to cope with).
But what about average temperatures? Do they bounce about all over the place too? Surely we have cold years and warm years? Bear with me! The results are really quite astonishing.
Let's start with just one single date, a month from now - 9th February - and try and predict what the maximum temperature will be that day, based on my records for the last 9 years:
So it looks like 9 Feb 2012 in my Sussex garden could be anywhere between about 5 degrees and 10 degrees, or conceivably a bit above or below - quite where in that range is anyone's guess. You won't find me betting on a figure!
But what will the average maximum temperature for February 2012 be in my garden?
Again, it's really difficult to predict what the average will be. Will it be 7 degrees or 10 degrees? That's how variable our weather is.
But the annual average temperature? Take a look at this graph, done to exactly the same scale.
Yes, we had a 'colder' year in 2010. But even in a 'cold' year, the average temperature only varies by about 1 degree Centigrade. Most years, the temperatures average themselves out like magic to almost precisely the same figure. I never expected that!
And that is the difference between climate and weather - climate is incredibly consistent, where weather is up and down like a yoyo
I hope you've stuck with me until now, because what this reveals is how powerful climate change is going to be. If our annual average temperatures warm by 2 degrees Centigrade in the next 50-100 years, which is looking like a conservative estimate these days, then you probably won't notice it day by day or month by month because weather masks the overall picture.We might have the odd day at 12 or 13 degrees, but we'll still have cold days.
But you can see that my third graph will look very different - instead of being steady at about 9 to 10 degrees, it will be steady at 11 to 12 degrees.
And, as climate has a massive bearing on what plants and creatures can live where, that will mean HUGE changes for our gardens and their wildlife.
The average temperatures surprised me, I expected a considerable difference. When I first worked out the average temperatures from my numbers, I reworked the sum a few times because I thought I’d got the result wrong.
If last winter’s low temperatures only caused the average temperature to drop by one degree, then I believe a rise of two degrees has got to make a very noticeable difference, hasn’t it?
If this current warm weather continues it will be interesting to see how it affects the yearly average.