In reply to Owen W-G:
With the exception of well trodden places like Bosigran, better to keep clear of non sea-level cliffs as they tend to hold more of the big furry lichens, which is what holds the moisture in. That said places like St Loy can be real sun traps.
Best bet is just to keep moving around. You may well find that Lizard is dry when Penwith is wet, or vice versa, or Dartmoor is wet when the culm is dry, etc, etc, but you won't know until the day.
You'll almost certainly find something, if you're prepared to move around a bit. CC guide should give aspects to help you choose crags to suit the conditions/prevailing wind etc. Everywhere dries pretty quick down here this time of year with a bit of wind.
Good luck!