Astronomical summer begins on Sunday, June 21, with the summer solstice, the yearly moment when the sun reaches its northernmost point in the sky. In Portland, that means nearly 15 hours and 41 minutes of daylight, with sunrise at 5:21 a.m. and sunset at 9:03 p.m.
Jim Todd said the word solstice comes from the Latin words sol, meaning sun, and sistere, meaning to stand still. That idea fits the day itself: on the June solstice, the sun reaches its peak northern position, and its zenith appears to pause before reversing direction and starting to move south again.
For people in Portland, the change is easy to measure. At noon on June 21, the sun is about 68 degrees above the southern horizon, the highest point it reaches in the city all year. By December, the winter solstice brings just under nine hours of daylight and a noon sun that reaches 21 degrees, a sharp reminder of how quickly the year turns after the longest day.
The June solstice is an astronomical marker, not a weather event, and it marks the start of a season that lasts nearly 93 days. It runs from the solstice to the September equinox, carrying the region through the stretch of the year when daylight slowly begins to shorten again.
The contrast is even starker near the Arctic Circle, where the June solstice is the only day of the year when all locations inside it experience 24 hours of continuous daylight. Because of atmospheric refraction, the midnight sun can still be visible a few days before and after the solstice from areas as far as 60 miles south of the Arctic Circle, and the farther north someone travels, the more days of the midnight sun they will experience.
So the date is not just the start of summer on the calendar. It is the point when daylight tops out, the sun turns back south, and the season begins the long slide toward the September equinox.
