Aurora Borealis in Mercer Island
United States · 47.57°, -122.22° · geomagnetic 53.1° · needs Kp 7
Tonight in Mercer Island
1%
Peak chance of a visible display tonight, from the same model the Revon app runs. Mercer Island needs Kp 7 to see anything at all, and tonight the forecast peaks at Kp 4.7. Short of the threshold, which is what most nights look like here.
Updated 2026-08-02 20:20 UTC
The next 30 nights in Mercer Island
Every night to come, scored the same way as tonight. The best of the open week is Sunday 2 Aug at 1%. Not one of the seven reaches the Kp 7 that Mercer Island needs, which is normal rather than unlucky — it averages 3.2 viable nights a year. The 23 nights past the seven-day window move with the 27-day solar rotation and are updated daily in the app.
Nights 8–30 unlock in the Revon app
See all 30 nights for Mercer Island
Revon aurora model over the NOAA Kp forecast and 27-day outlook
How often the aurora borealis reaches Mercer Island
3.2 nights a year, averaged across 10.0 years of records
| Storm level | Nights / year |
|---|---|
| Kp 4 | 83.4 |
| Kp 5 | 28.7 |
| Kp 6 | 9.3 |
| Kp 7 | 3.2 |
| Kp 8 | 1.2 |
NOAA planetary Kp, 2016-04-02 to 2026-03-30
Wait for an alert; do not book a week
At Kp 7, Mercer Island needs a severe geomagnetic storm before anything shows above the northern horizon. Storms that size arrive a handful of times per solar cycle and announce themselves a day or two ahead. Watching for one beats picking dates and hoping.
Hours of true darkness, month by month
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 11.5 | 10.3 | 8.8 | 6.6 | 4.1 | 1.9 | 3.0 | 5.7 | 8.0 | 9.9 | 11.2 | 11.8 |
Solar declination and hour angle at −18°
Getting clear of the light
Mercer Island is small enough that its own lights are a minor problem — the centre reads Bortle 8. Walking to the edge of town is often escape enough.
- 36 km east-south-east — around King County → Bortle 4
- 36 km east-south-east — around King County → Bortle 4
Falchi 2016 World Atlas (DOI: 10.5880/GFZ.1.4.2016.001)
The months that actually deliver
Counting only nights that were both stormy enough and dark enough, May, September and August came out ahead in Mercer Island. That is storm season and darkness overlapping — the equinoxes tend to be geomagnetically active, and the nights are already long by then.
Darkest nights of the coming year
A bright moon washes out a weak display as effectively as street lighting. These new moons fall inside the Mercer Island viewing season.
- 13 Aug 2026
- 11 Sep 2026
- 11 Oct 2026
- 09 Nov 2026
- 09 Dec 2026
- 07 Jan 2027
- 06 Feb 2027
Where it is close to a certainty
If you would rather plan a trip than wait for a storm, the nearest place with genuinely frequent aurora is Juneau, 1,442 km north-north-west in United States.
| Mercer Island | Juneau | |
|---|---|---|
| Kp needed | 7 | 5 |
| Nights per year | 3.2 | 28.7 |
| Geomagnetic latitude | 53.1° | 61.6° |
Confirmed reports from this area
60 verified sightings were logged within 300 km of Mercer Island between 2015-01-01 and 2016-12-31. Rare is not the same as impossible.
Aurorasaurus verified positive reports
Where the horizon opens up near Mercer Island
The display sits low on the northern horizon, so what beats a better forecast is open ground facing that way. Height gets you above the town glow; water gives you an unbroken skyline. These are within a short drive of Mercer Island.
- Burrows Landing Park — park3.1 km north-north-east
- Faben Point — cape3.4 km north-west
- Bellefields Nature Park — park3.6 km north-east
- Groat Point — cape4.2 km north
- Whalers Cove — bay4.3 km north-north-east
- Vista Meydenbauer Alcove — peak4.4 km north-north-east
Places from GeoNames (CC BY 4.0)
What to do with the daylight
Aurora watching is a night job, and in winter that leaves a short, bright day to fill. Close to Mercer Island you will find KMIH-FM (Mercer Island), KEZX-AM (Seattle) and KIXI-AM (Mercer Island), and for a day when the cloud sits low, Bellevue Art Museum, Rosalie Whyel Museum of Doll Art and Frye Art Museum are indoors and near by.
Keep the daylight loose: the sky decides the evening, and the forecast can turn within a few hours.
Places from GeoNames (CC BY 4.0)
Where to stay
Anywhere on the outskirts of Mercer Island will do; what matters is being able to step outside and check the sky without a drive first.
- Travelodge Mercer Island 2.2 km from the centre
- Hilton Bellevue 4.2 km from the centre
- Bellevue Club Hotel 4.4 km from the centre
- Homestead Seattle-Bellevue 4.4 km from the centre
- Extended Stay America Seattle Bellevue Factoria 4.4 km from the centre
- Residence Inn By Marriott Bellevue Downtown 4.5 km from the centre
Places from GeoNames (CC BY 4.0) — confirm before booking
The last nights it was visible here
Nights in the last decade when the storm was strong enough for Mercer Island and the sky was dark enough to show it.
| Date | Peak |
|---|---|
| 2026-03-20 | Kp 7.0 |
| 2026-01-20 | Kp 7.67 |
| 2026-01-19 | Kp 8.67 |
| 2025-11-12 | Kp 7.33 |
| 2025-11-11 | Kp 8.67 |
NOAA planetary Kp
Know when it is worth going outside
Revon watches the Mercer Island forecast and pushes an alert when the odds for tonight clear your threshold — no checking, no guessing.
Common questions about the aurora borealis in Mercer Island
Can you see the aurora borealis from Mercer Island?
Yes. On the last 10.0 years of NOAA Kp records, Mercer Island had about 3.2 nights a year when the storm was strong enough and the sky dark enough at the same time.
What Kp index do you need to see the aurora borealis in Mercer Island?
Kp 7. Mercer Island sits at geomagnetic latitude 53.1°, and the auroral oval only reaches that far from the pole once activity hits Kp 7. Storms that size occur about 3.2 nights a year.
When is the best time of year to see the aurora borealis in Mercer Island?
May, September and August. Those months scored highest once both conditions are counted together: geomagnetic activity and enough hours of real darkness.
Where can you escape the light pollution near Mercer Island?
The centre of Mercer Island reads Bortle 8. The nearest sky at Bortle 4 is about 36 km east-south-east around King County. On a marginal night that drive matters more than the forecast does.
Where is the nearest place to Mercer Island with reliable aurora borealis?
Juneau, United States — 1,442 km north-north-west. It needs only Kp 5 and averages 28.7 viable nights a year against 3.2 in Mercer Island.
Nearby towns
Forecasts for places within reach of Mercer Island.