I'm not sure it will be harder for the afternoon players. The rain made the course much softer and at the moment it's sunny (obviously the rain can come back at any moment).
I heard the commentators say on one of Koepka's shots that earlier in the day his ball would have rolled over the green rather than sticking pin high as it did.
I haven't been watching long enough to know if the wind is much different now than it was earlier. But even if the wind is blowing a bit more, it might be offset by the softer, more receptive, greens.