Days start getting shorter after the summer solstice, which falls on June 20 or 21 in the Northern Hemisphere. From that point forward, you lose daylight each day until the winter solstice in late December. In 2025, the summer solstice occurs on June 20 at 7:42 p.m. PDT, and in 2026 it shifts to June 21.
If you live in the Southern Hemisphere, the calendar flips: your days start shortening after the December solstice and reach their shortest point around June 20 or 21.
Why Days Shrink After the Solstice
Earth’s axis is tilted about 23.5 degrees relative to its orbit around the sun. This tilt is the entire reason seasons exist. During the Northern Hemisphere’s summer, the North Pole leans toward the sun, giving northern latitudes longer exposure to sunlight each day. At the summer solstice, that tilt is at its maximum effect, and the sun traces its highest, longest arc across the sky.
After that peak, Earth continues orbiting, and the North Pole gradually tilts away from the sun. Each day, the sun’s path across the sky gets a little lower and a little shorter. This continues until the winter solstice around December 21, when the Northern Hemisphere gets its fewest hours of daylight. Then the process reverses.
How Fast You Lose Daylight
The rate of daylight loss isn’t constant. It’s slowest right after the solstice, fastest around the equinoxes, and slow again near the winter solstice. Think of it like a pendulum: the change is gradual at the extremes and rapid in the middle.
Around the September equinox, mid-latitude locations lose about 2 to 3 minutes of daylight per day. That’s noticeable from week to week, roughly 15 to 20 minutes lost each week. In late June or late December, the change is barely perceptible, sometimes just seconds per day.
Your Latitude Changes Everything
How dramatically your days shrink depends heavily on where you live. Near the equator, daylight stays close to 12 hours year-round, with only minor seasonal variation. The closer you get to the poles, the more extreme the swing becomes.
At mid-latitudes like New York, London, or Seattle (roughly 40 to 50 degrees north), the difference between the longest and shortest day can be five to eight hours. In Anchorage, Alaska, the summer solstice brings nearly 22 hours of daylight, while the winter solstice delivers under 5.5 hours. At the Arctic and Antarctic Circles, the extremes reach 24-hour daylight in summer and 24-hour darkness in winter.
Earliest Sunset Doesn’t Match the Shortest Day
One detail that surprises most people: the earliest sunset of the year doesn’t happen on the winter solstice. At around 40 degrees north latitude, the earliest sunset actually occurs in early December, roughly two weeks before the solstice. Meanwhile, the latest sunrise doesn’t happen until around New Year’s Day.
This quirk exists because Earth’s orbit isn’t a perfect circle, and our 24-hour clock doesn’t perfectly match the sun’s actual movement across the sky. The length of a true solar day (measured from one solar noon to the next) varies by up to 30 seconds from the standard 24 hours. In late December, each solar day runs almost half a minute longer than clock time. This small daily drift shifts the sunrise and sunset times in ways that don’t line up neatly with the solstice. The winter solstice is still the day with the fewest total hours of sunlight, but the earliest sunset and latest sunrise bracket it on either side.
How Shorter Days Affect Your Body
The shift isn’t just astronomical. Your body tracks daylight through specialized cells in your eyes that send signals to a small region of the brain that acts as your master clock. This clock governs when you feel sleepy and when you feel alert, primarily by controlling the release of melatonin, the hormone that promotes sleep.
As days get shorter, your body produces melatonin for a longer stretch each night, which can make you feel drowsier and less energetic. Shorter daylight exposure also affects serotonin, a chemical involved in mood regulation. Light directly influences serotonin availability, so less sunlight can mean lower levels of this mood-stabilizing compound. For some people, this combination triggers Seasonal Affective Disorder (SAD), a form of depression with strong seasonal patterns. Bright light therapy, which involves sitting near a specially designed lamp each morning, is an established first-line treatment and often improves symptoms within a few days.
Even if you don’t experience SAD, you may notice changes in sleep patterns, appetite, or energy levels as autumn progresses. These are normal biological responses to the shifting light. Getting outdoor light exposure in the morning, especially during the shorter months, helps keep your internal clock synchronized and can offset some of the grogginess that comes with darker days.