1st September: the first day of meteorological autumn, which lasts for three months exactly, ending on the 30th November. Having grown up with seasons defined by equinoxes and solstices , it was until recently a strange concept to me that meteorologists use the actual calendar to define seasons. It turns out that statistics, calculations and averages of parameters such as rainfall and temperature are much friendlier in bunches of 30 / 31 days at a time, starting on the first day of the month. Especially in those prehistoric, pre-computer ages… (I kid; I only mean the 20th century).
A system whereby averages are calculated on a monthly basis works well to provide summaries of the climate, for each month of every year. The Met Office has been collating these for the UK since 2000, and it is interesting to note the method in which this is done. Bear with me, because I am learning about this as I write it out, which helps me solidify new information in my head. Most of this is information from the Met Office website – a pretty reliable source in these matters, to be honest… 
Approx. 250 weather stations around the UK provide real-time data, from which the Provisional Summaries are formulated. We can expect a provisional summary of August to appear by the 6th September; and a provisional summary of the entire summer season by the 7th September – and these will be the Met Office’s best current assessment. But for an even more accurate report, there are hundreds more rainfall and climate stations around the UK which are looked at by observers. Data from these flies into the hands of the assessors only a few days, if not weeks or months, later. Therefore, the final summaries don’t appear until up to six months later. They really are worth the wait though, because any scientist will know that the bigger your pool of data, the more reliable your calculations (excluding the anomalous little rascals).
But anyway; I have strayed somewhat from my original intention of this post, which was to formally exclaim: WOOHOO, Autumn is here! Definitely my favourite season of the year, with nature’s gorgeous palette really coming out and enhancing the beauty of a lengthening evening.