nightfall

at nightfall

Judging from the look of the sky, we might have a shower before nightfall.

The seals surface more frequently then, so a bear's chance of catching one at a breathing hole is greater after nightfall.

The police expect to apprehend the robber before nightfall.

Let's stay until nightfall and watch the fireworks.

If we leave now, we could be back in Tucson before nightfall.