Why the dark mornings peak before winter

Daylight saving time moves the clock an hour ahead of the sun. By late October the sun is already rising late, and the clock makes it look even later. On the first Sunday in November the clocks fall back, and sunrise jumps an hour earlier overnight. It then creeps later again through December, but it never quite gets back to where it was on the last Saturday of daylight time.

Why the earliest sunset isn’t on the shortest day

The shortest day is the solstice, around December 21. But in December, solar noon (when the sun is highest) drifts about half a minute later every day. Earth’s orbit is slightly oval, and it is moving fastest in early January, when it passes closest to the sun. That drift pushes both sunrise and sunset later. The day is still getting shorter until the solstice, but the drift wins in the evening, so sunsets start getting later in early December. In the morning the two effects add together, so sunrises keep getting later until early January.

Try the buttons above the chart. With standard time all year, the darkest morning moves back to January. With daylight time all year, it becomes a winter sunrise after 8:45 AM.