Can you see the northern lights in Tri-Cities in May?

On dark, clear nights with enough activity. 31 of 31 nights at Tri-Cities have civil darkness, and 1% of past May days reached Kp 7.

How dark is Tri-Cities in May?

Tri-Cities averages 7.7 hours of civil night a night in May 2027, from 8 h 23 min on the 1st to 7 h 6 min on the last night.

How cloudy is Tri-Cities in May?

NASA POWER's 2001 to 2020 climatology gives Tri-Cities's 1 degree cell 56% mean cloud in May, against 56% for the whole year. It is an all-hours average, not a forecast.

What is the best night in May 2027 for aurora in Tri-Cities?

By darkness and moon alone, May 1, 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 May or June better in Tri-Cities?

By civil night times the clear share, May scores 3.4 hours at Tri-Cities and June 3.7. June comes out ahead.

Tri-Cities · May 2027

Northern lights in Tri-Cities in May 2027

Answer

May gives Tri-Cities 7.7 hours of civil night on the 15th, the 10th darkest of its 12 months, under 56% mean cloud. 1% of May days since 1996 reached Kp 7, enough for the oval edge to reach Tri-Cities.

7.7 h

civil night, average night

SunCalc for 46.25, -119.20; NASA POWER; GFZ Kp

May against the rest of the year

2.9

4.0

3.4

3.6

3.4

3.7

5.4

6.2

6.3

5.3

4.0

3.2

May cloud at Tri-Cities averages 56% in NASA POWER's 2001 to 2020 record, close to its yearly mean of 56%. July is Tri-Cities's clearest month at 26%. By civil night times clear sky, May scores 3.4 hours at Tri-Cities, 10th of 12. Seattle, 282 km away, averages 70%, cloudier by 14 points.

Civil night at Tri-Cities starts May at 8 h 23 min and reaches 7 h 6 min by May 31, 1.3 hours shorter. SWPC's 10 PM to 2 AM window is fully dark on every night. True astronomical darkness, the sun 18 degrees down, lasts 4.3 hours on the 15th.

May night by night

May opens toward a new moon on May 6, with full moon on May 20, in America/Los_Angeles dates. Tri-Cities gets 121 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: May 1 (4 h), May 2 (4 h), May 3 (4 h).

1
19% lit
7.1 h
2
12% lit
7.3 h
3
6% lit
7.7 h
4
2% lit
8.0 h
5
0% lit
8.2 h
6
1% lit
7.7 h
New
7
5% lit
6.4 h
8
11% lit
5.3 h
9
19% lit
4.3 h
10
29% lit
3.6 h
11
40% lit
3.1 h
12
51% lit
2.6 h
13
62% lit
2.3 h
14
73% lit
1.9 h
15
82% lit
1.6 h
16
89% lit
1.2 h
17
95% lit
0.8 h
18
98% lit
0.3 h
19
100% lit
0.0 h
20
99% lit
0.4 h
Full
21
97% lit
1.4 h
22
92% lit
2.2 h
23
86% lit
2.8 h
24
79% lit
3.3 h
25
71% lit
3.7 h
26
62% lit
4.0 h
27
53% lit
4.3 h
28
43% lit
4.5 h
29
34% lit
4.8 h
30
24% lit
5.1 h
31
16% lit
5.4 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 Mays

Tri-Cities needs Kp 7 for the average oval edge to sit overhead. 13 of the 930 May days from 1996 to 2025 (1%) reached it in the GFZ Potsdam record, 5th of 12 months; storm days with Kp 5 or more made up 10%. 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.

May across United States

Tri-Cities ranks 4th in United States for civil night on May 15, behind Buffalo at 8.1 hours. Coming from April (9.2 hours at Tri-Cities), May loses darkness, and June brings shorter nights (6.8 hours on the 15th).

Civil night on May 15 and May cloud, month-page towns in United States
Town	Civil night	Cloud
Buffalo	8.1 h	65%
Portland, Maine	8.0 h	66%
Minneapolis	7.9 h	63%
Tri-Cities	7.7 h	56%
Duluth	7.6 h	65%
Fargo	7.6 h	61%
Seattle	7.5 h	70%
Juneau	5.1 h	74%
Anchorage	3.8 h	79%
Eagle River	3.7 h	79%
Fairbanks	0.0 h	70%

Darkness and moon, every night

Tri-Cities, May 2027: each night from local noon to the next noon
Night	Civil	Astronomical	Moon-free dark	Moon-free, 10 PM to 2 AM	Moon lit
Sat May 1	8 h 23 min	5 h 23 min	7 h 5 min	4 h	19%
Sun May 2	8 h 20 min	5 h 18 min	7 h 21 min	4 h	12%
Mon May 3	8 h 17 min	5 h 14 min	7 h 39 min	4 h	6%
Tue May 4	8 h 14 min	5 h 9 min	8 h 1 min	4 h	2%
Wed May 5	8 h 11 min	5 h 4 min	8 h 11 min	4 h	0%
Thu May 6	8 h 8 min	5 h	7 h 43 min	4 h	1%
Fri May 7	8 h 5 min	4 h 55 min	6 h 25 min	3 h 29 min	5%
Sat May 8	8 h 2 min	4 h 50 min	5 h 16 min	2 h 22 min	11%
Sun May 9	7 h 59 min	4 h 46 min	4 h 20 min	1 h 28 min	19%
Mon May 10	7 h 56 min	4 h 41 min	3 h 37 min	46 min	29%
Tue May 11	7 h 53 min	4 h 36 min	3 h 4 min	14 min	40%
Wed May 12	7 h 50 min	4 h 32 min	2 h 37 min	0 min	51%
Thu May 13	7 h 47 min	4 h 27 min	2 h 15 min	0 min	62%
Fri May 14	7 h 45 min	4 h 22 min	1 h 54 min	0 min	73%
Sat May 15	7 h 42 min	4 h 18 min	1 h 34 min	0 min	82%
Sun May 16	7 h 39 min	4 h 13 min	1 h 13 min	0 min	89%
Mon May 17	7 h 37 min	4 h 8 min	49 min	0 min	95%
Tue May 18	7 h 34 min	4 h 4 min	21 min	0 min	98%
Wed May 19	7 h 31 min	3 h 59 min	0 min	0 min	100%
Thu May 20	7 h 29 min	3 h 55 min	24 min	0 min	99%
Fri May 21	7 h 27 min	3 h 50 min	1 h 22 min	32 min	97%
Sat May 22	7 h 24 min	3 h 46 min	2 h 10 min	1 h 21 min	92%
Sun May 23	7 h 22 min	3 h 41 min	2 h 47 min	2 h	86%
Mon May 24	7 h 20 min	3 h 37 min	3 h 17 min	2 h 31 min	79%
Tue May 25	7 h 17 min	3 h 32 min	3 h 40 min	2 h 55 min	71%
Wed May 26	7 h 15 min	3 h 28 min	4 h	3 h 16 min	62%
Thu May 27	7 h 13 min	3 h 24 min	4 h 16 min	3 h 34 min	53%
Fri May 28	7 h 11 min	3 h 20 min	4 h 32 min	3 h 51 min	43%
Sat May 29	7 h 9 min	3 h 16 min	4 h 48 min	4 h	34%
Sun May 30	7 h 7 min	3 h 12 min	5 h 5 min	4 h	24%
Mon May 31	7 h 6 min	3 h 8 min	5 h 25 min	4 h	16%

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 May?: On dark, clear nights with enough activity. 31 of 31 nights at Tri-Cities have civil darkness, and 1% of past May days reached Kp 7.
How dark is Tri-Cities in May?: Tri-Cities averages 7.7 hours of civil night a night in May 2027, from 8 h 23 min on the 1st to 7 h 6 min on the last night.
How cloudy is Tri-Cities in May?: NASA POWER's 2001 to 2020 climatology gives Tri-Cities's 1 degree cell 56% mean cloud in May, against 56% for the whole year. It is an all-hours average, not a forecast.
What is the best night in May 2027 for aurora in Tri-Cities?: By darkness and moon alone, May 1, 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 May or June better in Tri-Cities?: By civil night times the clear share, May scores 3.4 hours at Tri-Cities and June 3.7. June comes out ahead.

Sources and verification

SunCalchttps://github.com/mourner/suncalc
NASA POWER climatologyhttps://power.larc.nasa.gov/docs/services/api/temporal/climatology/
GFZ Potsdam Kp indexhttps://kp.gfz.de/en/data
NOAA SWPC, Tips on viewing the aurorahttps://www.spaceweather.gov/content/tips-viewing-aurora

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.