In reply to Nicholas Livesey:
To be honest, Nick, I find that I don't need to know to that level of accuracy. If it's in mid-summer, and I'm shooting at sunset, then I know to expect light from quite far to the north-west. Etc. There are so many other variables at play that I found it wasn't critical, so these days I tend not to bother with it.
Post edited at 00:23