When is northern lights season?

Where you are, it is the run of dates with enough darkness. The tool computes it for your coordinates using at least 4 hours of civil night between 18:00 and 06:00.

Why does my location have a season all year?

In Glow's scan, points at 55 degrees latitude or lower, in a time zone near local solar time, have at least 4 hours of civil night every evening, so darkness never closes the season there.

Can I see the northern lights in summer?

Only where the sun reaches -6 degrees. The no-darkness row shows the dates when it does not, for your coordinates.

What does the bone hatch on the ribbon mean?

Hours when the moon is above the horizon while the sun is at or below -6 degrees. It repeats in a diagonal pattern as the moon rises about an hour later each night.

ToolComputedCited

When does aurora season start and end where I live?

Answer

At Tromsø, the dark season (at least 4 hours of civil night between 18:00 and 06:00) runs from August 23 to April 18 across New Year. There is no civil darkness at all from April 27 to August 14.

239 days

dark season at Tromsø, 2026

SunCalc sun altitude for all 365 nights

At Tromsø, the dark season (at least 4 hours of civil night between 18:00 and 06:00) runs from August 23 to April 18 across New Year. There is no civil darkness at all from April 27 to August 14.

Civil twilightNautical twilightAstronomical nightMoon up in darkness10 PM to 2 AM, SWPC best windowToday

Aurora season

Aug 23 to Apr 18

239 days with at least 4 h of civil night between 18:00 and 06:00 (Glow's definition)

SunCalc, 15 minute samples

No-darkness season

Apr 27 to Aug 14

110 nights with the sun above -6° all night

Longest night

Dec 19

19 h 17 min of civil night

Civil night per year

3,178 h

Sum of all 365 nights

Equinoxes

Mar 20, Sep 23

Computed from the sun's apparent longitude, in your time zone

Worked example

Compare two Glow places for 2026. Every evening of the year at Seattle has at least 4 hours of civil night between 18:00 and 06:00, so darkness never closes the season. Every night of the year has some civil darkness. At Fairbanks, the dark season (at least 4 hours of civil night between 18:00 and 06:00) runs from August 9 to May 1 across New Year. There is no civil darkness at all from May 13 to July 28.

Seattle's longest night is 14.3 hours of civil night on December 17, 2026; Fairbanks reaches 17.3 hours on December 19, 2026. The ribbon shows the same contrast as shape: a thick band all year in Seattle, and a band that pinches to nothing in Fairbanks each summer.

Reading the night ribbon

The ribbon is a year on one strip. Each column is one day, January on the left. Each row is half an hour of local clock time, from noon at the top through midnight in the middle to noon again at the bottom. Glow fills every cell from SunCalc: pale periwinkle for civil twilight, deeper periwinkle for nautical twilight, navy for astronomical night, and a bone hatch where the moon is up while it is dark.

The band's height is the length of the night. Where the band pinches to nothing in midsummer, the place has white nights. The faint horizontal band marks 10 PM to 2 AM, SWPC's recommended window, and the green line marks today.

How Glow defines the season

There is no official start date for aurora season. Glow uses a stated rule: a day belongs to the dark season when the evening from 18:00 to 06:00 local time holds at least 4 hours of civil night. The season is the longest run of such days, joined across New Year.

The no-darkness season is the longest run of nights when the sun never reaches -6 degrees. Glow computes both from 15 minute samples of the sun's altitude with interpolated crossings, for every day of the year you pick.

The equinox note

SWPC's viewing tips name the spring and fall equinoxes as the best seasons for aurora watching. Glow quotes that and lists the equinox dates for your year, computed from the sun's apparent longitude and shown in your time zone.

Glow does not add a mechanism or a percentage to that statement. At high latitudes the equinoxes also sit inside the dark season, so a trip timed near one gets both.

Questions

When is northern lights season?: Where you are, it is the run of dates with enough darkness. The tool computes it for your coordinates using at least 4 hours of civil night between 18:00 and 06:00.
Why does my location have a season all year?: In Glow's scan, points at 55 degrees latitude or lower, in a time zone near local solar time, have at least 4 hours of civil night every evening, so darkness never closes the season there.
Can I see the northern lights in summer?: Only where the sun reaches -6 degrees. The no-darkness row shows the dates when it does not, for your coordinates.
Why are the equinoxes mentioned?: SWPC's viewing tips name the spring and fall equinoxes as the best seasons for aurora watching. Glow quotes that line and lists the dates.
What does the bone hatch on the ribbon mean?: Hours when the moon is above the horizon while the sun is at or below -6 degrees. It repeats in a diagonal pattern as the moon rises about an hour later each night.