Any thoughts on how sunny it must be for this special ability to take effect?

We can of course base our judgement on the passage from the LotR book found below the special ability's name in the LM book, but I would very like some other exemples.

What about Mirkwood? It's pretty dark in there, right? I guess if the sky is dark, the forest will be worse.

Thanks for sharing your thoughts!

I note that the description for Denizens of the Dark, found on LB pg66 says:

Which certainly would suggest that dense forest should be considered dark.

Bear in mind that "Hate Sunlight" and "Denizens of the Dark" are two separate abilities.

So, in answer to the OP with regard to Hate Sunlight, I'd personally NOT apply it in overcast, very cloudy, and/or stormy weather. I think that offers the dramatic possibility of such things changing during the encounter and affecting the battle accordingly when the storm clouds break and shafts of sunlight pierce the sky and bathe the land in light. This would mean that creatures losing a point of Hate, maybe their last, would flee (if Craven) or become wearied and the tide of the battle would turn in the fellowship's favour!

Nice suggestion as always Rich. Man you've certainly got a nose for the dramatic! I sure hope I can bring that off in my game at some point.

ISTR thinking that there is some slight ambiguity about the wording of Hate Sunlight (don't have books with me, sorry). I think it's to do with when exactly is the first time you attack an enemy - the first time in a combat? i.e. once per combat, or the first time you attack a specific enemy? i.e. multiple times per combat. It feels like it ought to be the second I think, else it would be a bit weak.

It says:

The creature loses one point of Hate at the end of the first round of combat fought while exposed to the light of the sun.

... So, I'd say its at the end of the first round of combat the creature has been involved in - whether that's as a melee or missile combatant and it doesn't matter who their opponent is/are.