It depends on how hot it is the next day, how heavy the rain was, how long it rained for and how long after the rain you go to ride.
That said, manly dam had pretty good drainage and less than a day later most of the water will be gone, with a few puddles here and there. Just remember those wooden board walks get slippery when wet.
hope this helps

I rode it yesterday and all of the loop was completely bone dry. Actually, I can't remember when the Dam was last in that condition. Anyway, my silly pondering aside, even today the lap should still be okay to do, as the rain was only scattered and not too heavy. If that was your point?

And then sporadic most of the afternoon in Brookvale today...
Depends on how much rain falls tonight.

yeah it got pretty heavy in Balgowlah at one point, but its cleard up, so it should be good