Somewhere above the clouds, it's a bright sunny day, but down here in Portland, it's raining. It may be daytime, but it's dark. If you're driving your car, turn on your headlights. It's the safe thing to do. It's the law. It's so easy to twist the little switch that turns on your lights.
Most people get this, but a surprising number of Portland drivers leave their lights off, no matter how heavily it's raining. I estimate it to be around 15-20%. If you fit into this group, please change your ways or do the rest of Portland a favor and move to the desert.