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Aurora forecast: how high will the Kp index reach?

The planetary K-index (Kp, 0–9) measures how disturbed Earth's magnetic field is, and it is the number aurora chasers watch. Each day Norynta asks how high Kp will reach over the UTC day: quiet (2+ or lower), unsettled (3), active (4) or storm (5- or higher). At storm level the aurora often reaches well beyond the Arctic, into places such as Scotland, southern Scandinavia, much of Canada and the northern United States; on quiet days it usually stays near the polar regions. Below are the crowd's live odds, the settlement rule and the recent track record.

Last 4 days: Unsettled (Kp 3-, 3 or 3+) happened on 2 of 4 days. Players: no forecasts yet — be the first. See the record

Live question · Tuesday, October 20

How high will the Kp index (geomagnetic activity) reach on Tuesday, October 20 (UTC)?

Make your call: tap a range. No account needed.

Forecasts close Tue, Oct 20, 12:00 AM UTC

No forecasts yet: every range opens at equal odds. Be the first.

Free play credits · no real money · settled automaticallyFull question, chart & your own probability →

How it settles

Settles to the level containing the highest of the eight 3-hour planetary Kp values for the UTC day, as published by NOAA SWPC. Levels: Quiet below 2.5, Unsettled 2.5 to below 3.5, Active 3.5 to below 4.5, Storm 4.5 or higher (Kp 5- and up, about G1). Trading closes when the day begins; the result is read 3 hours after it ends. Later revisions are not applied.

Official source: NOAA Space Weather Prediction Center, estimated planetary K-index (3-hourly)

Track record

Can you beat the base rate?

  • 1/4
    Quiet (Kp 2+ or lower)
  • 2/4
    Unsettled (Kp 3-, 3 or 3+)
  • 1/4
    Active (Kp 4-, 4 or 4+)
  • 0/4
    Storm (Kp 5- or higher)

Always answering “Unsettled (Kp 3-, 3 or 3+)” would have been right 2 of 4 days. Read the conditions better than that and you beat the base rate.

Make your call
DayResultPlayers
Sunday, October 18Quiet (Kp 2+ or lower) (Kp 2+)No forecasts yet
Saturday, October 17Unsettled (Kp 3-, 3 or 3+) (Kp 3)No forecasts yet
Friday, October 16Active (Kp 4-, 4 or 4+) (Kp 4-)No forecasts yet
Thursday, October 15Unsettled (Kp 3-, 3 or 3+) (Kp 3)No forecasts yet

Voided questions are left out. Site-wide scoring is on How accurate is the crowd?

Questions

Will there be a geomagnetic storm (aurora) tomorrow?
For Tuesday, October 20, nobody has forecast yet, so the ranges still sit at their opening odds (Quiet (Kp 2+ or lower): 25%; Unsettled (Kp 3-, 3 or 3+): 25%; Active (Kp 4-, 4 or 4+): 25%; Storm (Kp 5- or higher): 25%). Make the first forecast on the live card; the odds move as people forecast.
How accurate is the crowd?
Not measured yet: none of the last 4 settled days had player forecasts, so there is no crowd score to report. Meanwhile, over the last 4 settled days, Unsettled (Kp 3-, 3 or 3+) happened on 2 of 4 days. Every forecast question is scored with a Brier score as soon as it resolves.
What Kp do I need to see the northern lights?
It depends on how far you are from the magnetic pole. Near the Arctic Circle the aurora is common even at Kp 2–3. Mid-latitude places usually need a geomagnetic storm: Kp 5 or higher (G1), and more for locations further south. Clear, dark skies away from city light matter as much as Kp.
Where does the Kp value come from?
NOAA's Space Weather Prediction Center publishes the estimated planetary K-index every three hours. The question uses the highest of the day's eight values, read 3 hours after the UTC day ends.
Is this real money or betting?
No. Norynta uses free play credits only. There are no deposits, no withdrawals and nothing to cash out; the point is to see how good your forecasts are and how the crowd compares with official data.