piperarcher,
as requested, i did the weekend stats. Figures seem slightly better in some months and slightly worse in others. I think 5 years is too short to pick up any significant 'weekend' trend.
Mth AllDays WkEnd
Jan 47.56% 57.67%
Feb 45.14% 46.15%
Mar 54.86% 55.15%
Apr 68.69% 70.41%
May 69.87% 73.57%
Jun 74.62% 70.52%
Jul 74.10% 75.78%
Aug 67.80% 74.29%
Sep 67.93% 72.38%
Oct 64.11% 63.29%
Nov 47.05% 44.62%
Dec 53.89% 60.55%
What is interesting though is I ran the numbers again for 08:00 till 10:00 and for 14:00 till 16:00, and there is a 10-15% increased chance of better weather between 14-16. Now if i can figure out how to attach a chart in pprune I can show this better...