I was thinking along the lines of added a time range to the event trigger so that daytime and nighttime could be defined for that event. Instead of 'happen if daytime', it would be 'happen if this time' with start and stop times given by the designer.
There was an item on the UA wishlist to provide an event that can trigger at a specific time no matter what other events were happening (or even if none are). Such a thing would require a type of global event list that would get scanned with every game clock tick to look for events that should trigger. It's not something DC is made to handle right now.
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CocoaSpud
Dungeon Craft Development Team
http://uaf.sourceforge.net