What time of night is best for the northern lights?

SWPC's aurora page describes how a typical display develops. It mentions arcs that stretch across the sky in the evening, then twist and sway near midnight, when the display can fill the sky at the peak of a substorm. In the early morning the forms turn diffuse and patchy.

Activity stretches the window. SWPC notes that the hours of active aurora expand toward evening and morning as geomagnetic activity increases. On a quiet night at a high-latitude town, the few hours around midnight are the core. During a storm, aurora can show soon after dark and last until dawn twilight.

SWPC gives the window in local clock time. The sky, though, follows the sun. Solar midnight is the moment the sun reaches its lowest point below your horizon, halfway between sunset and sunrise. It lands on 00:00 only if your town sits at the center of its time zone and daylight saving is off.

Most towns sit off center. A town at the western edge of its zone sees the sun set late and reach its lowest point after 00:00. Daylight saving adds an hour on top. So while daylight saving is on, solar midnight in many US towns falls near 01:00 on the clock.

The table shows solar midnight for the 10 Glow places on the coming December 15, with the offset from 00:00, the sun's depth at that moment, and how many of the 4 window hours are civilly dark.

Glow applies SWPC's window in the local time zone of the night's date, so daylight saving moves it with the clock, as the wording implies. The dark hours calculator counts how many minutes inside 22:00 to 02:00 are dark for any place and date. The solar midnight tool gives the sun's lowest point and its altitude.

• Be outside by 22:00 and stay past solar midnight if you can.
• If the live oval map shows the oval pushing south early, go out as soon as it is dark.
• Near the solstice at high latitude the whole night is dark, so the window matters more than the dusk time.
• Near midsummer at high latitude the window can be light; see the midnight sun guide.

The moon also moves through the night. A moon that sets at 23:00 leaves the core of the window dark. The moon planner and the best nights tool count only the minutes inside the window that are both dark and moon-free.

At the Alaska towns, Alaska time is set well east of the sun's position, so the sun's lowest point comes after 00:00 on the clock. At Reykjavik, Iceland keeps UTC all year while sitting about 22 degrees west, which pushes solar midnight past 01:00. Tromsø, on Central European time at 19 degrees east, sees the sun's lowest point shortly before 00:00 in winter.

None of this changes when aurora happens in physical terms. It changes which clock hours you should be outside. If you are planning from home for a trip, check the table for your destination rather than assuming midnight means 00:00.