DETROIT – The winter solstice, occurring in mid-December each year, signifies the official start of winter -- which, to some, might not be cause for celebration. However, the day also happens to signify something else: the welcomed pivot back to longer days and shorter nights.
Now that we’re past the winter solstice of December 2023, Metro Detroit’s sunrises will happen earlier and earlier, and the sunsets will happen later and later. But at what rate does this daylength -- the period of light between sunrise and sunset -- increase? And when does it reach its peak?
Here’s a deeper look.
What are the summer, winter solstices?
Each year, the earth’s Northern Hemisphere experiences a summer solstice in mid-June, and a winter solstice in mid-December. In the U.S., our summer solstice occurs the day when the sun is shining most directly on the Northern Hemisphere, causing temperatures to be warmer here. This is the official beginning of summer.
The earth then continues its orbit around the sun, spinning on its slightly tilted axis. When mid-December rolls around, the sun is instead shining directly on the Southern Hemisphere, and indirectly on the Northern Hemisphere, causing colder temperatures there. This is the official beginning of winter for the Northern Hemisphere.
On the day of the summer solstice, the Northern Hemisphere experiences its longest day and shortest night of the year. After that, our daylength gradually shrinks until the winter solstice arrives, representing the shortest day and longest night of the year for this hemisphere.
Daylength in Metro Detroit peaks at over 15 hours in June, and by December, shrinks to nine hours and some change. These increases and decreases happen slowly over the course of months, rather than all at once.
How much more daylight do we get each day after the winter solstice?
In the weeks that follow the winter solstice, the daylength in Metro Detroit will slowly get longer and longer -- but the exact amount of additional daylight varies by day, and by season. Experts say the rate of the change in daylength also depends on your specific latitude, and could be impacted by atmospheric conditions, as well.
Generally, you can expect the Midwest to gain a couple additional minutes of daylight each day, though that amount is not consistent the whole time.
When looking back on data from 2022-2023, the daylength in Metro Detroit increased by four minutes total between the winter solstice, Dec. 22, 2022, and New Year’s Eve that year. The increase in daylength began slowly immediately after the winter solstice, but ramped up to about two additional minutes of daylight per day by late January.
Throughout February, March, and the first half of April 2023, the daylength increased by about two and a half minutes each day. By the end of April, the rate of the increase had slowed, and dropped below two minutes by mid-May. The rate of the increase consistently slowed through May and June until the summer solstice occurred on June 21, 2023.
For the 2023 summer solstice, daylength in Metro Detroit peaked at 15 hours and 16 minutes. On that day, the region gained only an additional second of daylength compared to the day before.
The graph below shows how many minutes of additional daylength were recorded on select days between the 2022 winter solstice, and the 2023 summer solstice. The rate of increase tends to trend upward before it plateaus for a while, and then descends.
So, when will we see more sun in 2024?
Our daylight in Metro Detroit will gradually increase from now until June.
About one month after the 2022 winter solstice, which saw only nine hours of daylength, the daylight increased by about a half hour. Daylight lasted for 10 hours by early February, 11 hours by late February, 12 hours by mid-March, and 13 hours by early April in 2023.
All of this to say: The first few months of 2024 will still be fairly dark, but the change is already underway. The longer daylength will become more obvious by March and April.
It is projected that the Detroit area’s daylength will peak at 15 hours and 20 minutes when this year’s summer solstice arrives on June 20.