Um, how about "the weekend's over"?

[debgeisler]

Some Californians are scratching their heads over the behavior of a mother and calf whale who wandered 90 miles up the Sacramento River, then turned around yesterday and headed for open water late yesterday afternoon:

The humpback mother and her calf started moving southwest on the Sacramento River at around 3:30 p.m. and were about five miles outside the Port of Sacramento late Sunday afternoon, Coast Guard Petty Officer Brian Leshak said.

"Nothing triggered it. They just started moving on their own," Leshak said.

What triggered it? Wanting to avoid the "end of the weekend" rush on California highways. I'd want to get an early start, too.