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Tri-Cities · December 2026

Northern lights in Tri-Cities in December 2026

Answer

December gives Tri-Cities 14.1 hours of civil night on the 15th, the darkest month of its year, under 77% mean cloud. 0% of December days since 1996 reached Kp 7, enough for the oval edge to reach Tri-Cities.
14.1 h
civil night, average night
SunCalc for 46.25, -119.20; NASA POWER; GFZ Kp

December against the rest of the year

December cloud at Tri-Cities averages 77% in NASA POWER's 2001 to 2020 record, 21 points cloudier than its yearly mean. July is Tri-Cities's clearest month at 26%. By civil night times clear sky, December scores 3.2 hours at Tri-Cities, 11th of 12. Seattle, 282 km away, averages 79%, cloudier by 2 points.

Civil night at Tri-Cities starts December at 13 h 54 min and reaches 14 h 4 min by December 31 as the nights lengthen by 0.2 hours. SWPC's 10 PM to 2 AM window is fully dark on every night. True astronomical darkness, the sun 18 degrees down, lasts 11.6 hours on the 15th.

December night by night

December opens toward a new moon on Dec 8, with full moon on Dec 23, in America/Los_Angeles dates. Tri-Cities gets 235 hours of civil night with the moon below the horizon across the month. The best of them for moon-free darkness inside 10 PM to 2 AM: Dec 3 (4 h), Dec 4 (4 h), Dec 5 (4 h).

  1. 1

    39% lit

    8.0 h

  2. 2

    29% lit

    9.2 h

  3. 3

    20% lit

    10.3 h

  4. 4

    13% lit

    11.5 h

  5. 5

    7% lit

    12.7 h

  6. 6

    3% lit

    13.8 h

  7. 7

    1% lit

    14.0 h

  8. 8

    0% lit

    14.0 h

  9. 9

    2% lit

    14.1 h

  10. 10

    5% lit

    13.6 h

  11. 11

    9% lit

    12.5 h

  12. 12

    16% lit

    11.4 h

  13. 13

    23% lit

    10.3 h

  14. 14

    32% lit

    9.2 h

  15. 15

    41% lit

    8.1 h

  16. 16

    51% lit

    7.0 h

  17. 17

    61% lit

    5.8 h

  18. 18

    71% lit

    4.6 h

  19. 19

    81% lit

    3.3 h

  20. 20

    89% lit

    1.9 h

  21. 21

    95% lit

    0.6 h

  22. 22

    99% lit

    0.0 h

  23. 23

    100% lit

    0.0 h

  24. 24

    97% lit

    0.2 h

  25. 25

    92% lit

    1.6 h

  26. 26

    85% lit

    3.0 h

  27. 27

    76% lit

    4.4 h

  28. 28

    66% lit

    5.7 h

  29. 29

    55% lit

    6.8 h

  30. 30

    45% lit

    8.0 h

  31. 31

    35% lit

    9.2 h

Each cell is the night that starts on that date. Hours are civil-dark time with the moon below the horizon; the green rule scales with them. Green outline: new moon. Bone outline: full moon.

Activity in past Decembers

Tri-Cities needs Kp 7 for the average oval edge to sit overhead. 2 of the 930 December days from 1996 to 2025 (0%) reached it in the GFZ Potsdam record, one of the three quietest months for that level; storm days with Kp 5 or more made up 5%. Tri-Cities sits at 52.1 degrees geomagnetic. The lowest NOAA storm level whose typical viewing latitude reaches it is G3 (Kp = 7). By SWPC's rule the average oval edge is overhead only at Kp 7.

December across United States

Tri-Cities ranks 8th in United States for civil night on December 15, behind Fairbanks at 17.2 hours. Coming from November (13.4 hours at Tri-Cities), December adds darkness, and January brings shorter nights (13.7 hours on the 15th). The December solstice falls on December 21, 12:49 Tri-Cities time.

Civil night on December 15 and December cloud, month-page towns in United States
TownCivil nightCloud
Fairbanks17.2 h59%
Anchorage16.3 h72%
Eagle River16.3 h72%
Juneau15.7 h80%
Seattle14.3 h79%
Duluth14.2 h71%
Fargo14.2 h68%
Tri-Cities14.1 h77%
Minneapolis14.0 h69%
Portland, Maine13.9 h66%
Buffalo13.8 h85%

Darkness and moon, every night

Tri-Cities, December 2026: each night from local noon to the next noon
NightCivilAstronomicalMoon-free darkMoon-free, 10 PM to 2 AMMoon lit
Tue Dec 113 h 54 min11 h 27 min7 h 58 min2 h 48 min39%
Wed Dec 213 h 55 min11 h 28 min9 h 9 min3 h 58 min29%
Thu Dec 313 h 56 min11 h 29 min10 h 20 min4 h20%
Fri Dec 413 h 58 min11 h 30 min11 h 30 min4 h13%
Sat Dec 513 h 59 min11 h 31 min12 h 40 min4 h7%
Sun Dec 614 h11 h 32 min13 h 48 min4 h3%
Mon Dec 714 h 1 min11 h 33 min14 h 1 min4 h1%
Tue Dec 814 h 2 min11 h 34 min14 h 2 min4 h0%
Wed Dec 914 h 3 min11 h 34 min14 h 3 min4 h2%
Thu Dec 1014 h 4 min11 h 35 min13 h 33 min4 h5%
Fri Dec 1114 h 4 min11 h 36 min12 h 30 min4 h9%
Sat Dec 1214 h 5 min11 h 36 min11 h 24 min4 h16%
Sun Dec 1314 h 6 min11 h 37 min10 h 18 min4 h23%
Mon Dec 1414 h 6 min11 h 37 min9 h 12 min4 h32%
Tue Dec 1514 h 7 min11 h 38 min8 h 6 min3 h 10 min41%
Wed Dec 1614 h 7 min11 h 38 min6 h 58 min2 h 2 min51%
Thu Dec 1714 h 7 min11 h 38 min5 h 49 min52 min61%
Fri Dec 1814 h 8 min11 h 39 min4 h 35 min0 min71%
Sat Dec 1914 h 8 min11 h 39 min3 h 16 min0 min81%
Sun Dec 2014 h 8 min11 h 39 min1 h 55 min0 min89%
Mon Dec 2114 h 8 min11 h 39 min34 min0 min95%
Tue Dec 2214 h 8 min11 h 39 min0 min0 min99%
Wed Dec 2314 h 8 min11 h 39 min0 min0 min100%
Thu Dec 2414 h 7 min11 h 38 min12 min0 min97%
Fri Dec 2514 h 7 min11 h 38 min1 h 38 min0 min92%
Sat Dec 2614 h 7 min11 h 38 min3 h 3 min0 min85%
Sun Dec 2714 h 6 min11 h 37 min4 h 23 min0 min76%
Mon Dec 2814 h 6 min11 h 37 min5 h 39 min35 min66%
Tue Dec 2914 h 5 min11 h 36 min6 h 51 min1 h 48 min55%
Wed Dec 3014 h 5 min11 h 36 min8 h 2 min3 h45%
Thu Dec 3114 h 4 min11 h 35 min9 h 12 min4 h35%
Moon lit: SunCalc illuminated fraction at the middle of the 10 PM to 2 AM window.

Questions

Can you see the northern lights in Tri-Cities in December?
On dark, clear nights with enough activity. 31 of 31 nights at Tri-Cities have civil darkness, and 0% of past December days reached Kp 7.
How dark is Tri-Cities in December?
Tri-Cities averages 14.1 hours of civil night a night in December 2026, from 13 h 54 min on the 1st to 14 h 4 min on the last night.
How cloudy is Tri-Cities in December?
NASA POWER's 2001 to 2020 climatology gives Tri-Cities's 1 degree cell 77% mean cloud in December, against 56% for the whole year. It is an all-hours average, not a forecast.
What is the best night in December 2026 for aurora in Tri-Cities?
By darkness and moon alone, Dec 3, with 4 h of moon-free darkness inside 10 PM to 2 AM at Tri-Cities. Activity on that date will only be known hours ahead.
Is December or January better in Tri-Cities?
By civil night times the clear share, December scores 3.2 hours at Tri-Cities and January 2.9. December comes out ahead.

Sources and verification

Quoted figures last checked against their sources on 2026-09-30; next review 2026-12-31. Computed figures come from SunCalc and the IGRF-14 dipole as described in the methodology. Every quote is listed in the sources ledger.