The duration of the longest day depends on the latitude. The farther you are from the equator, the longer the day.
Some examples for the day length at the summer solstice in the northern hemisphere:
- In Miami, FL (25° 46' 27' N - 80° 11' 38'' W), the day length on June 21, 2023 is 13.75 hours (13h 45min 3sec). The sun rises at 6:30AM and sets at 8:15PM.
- In San Francisco, CA (37° 46' 45'' N - 122° 25' 10'' W), the day length on June 21, 2023 is 14.78 hours (14h 47min). The sun rises at 5:48AM and sets at 8:35PM.
- In New York, NY (40° 43' 50'' N - 73° 59' 12'' W), the day length on June 21, 2023 is 15.1 hours (15h 5min 52sec). The sun rises at 5:24AM and sets at 8:30PM.
- In Anchorage, AK (61° 12' 58'' N - 149° 53' 42'' W), the day length on June 21, 2023 is 19.38 hours (19h 22min 36sec). The sun rises at 4:20AM and sets at 11:42PM.
- North of the Arctic Circle, the sun does not set at all during this time of year. It is sometimes referred to as Midnight Sun.
The app LunaSolCal calculates the date and time of the summer solstice as well as the length of day depending on the selected location and year: