How disturbed Earth's magnetic field is, on a scale from 0 to 9, and what that means for aurora
Earth's magnetic field was calm. The auroral oval stays close to the poles at this level, so aurora is within reach mainly at high latitudes such as northern Scandinavia, Iceland, Alaska and northern Canada.
This is NOAA's value for the three hours from 18:00 to 21:00 UTC, the most recent block published. It is one number for the whole planet, and a guide to how far aurora reaches rather than a guarantee of seeing it.
At Kp 2.0, aurora is within reach of 117 of the 243 places we track, given a dark, clear sky. Find the Kp your location needs
One bar for each 3-hour block NOAA has published, from 21:00 UTC on Oct 5 to 21:00 UTC on Oct 6. The number under each bar is the UTC hour its block starts.
Bars show NOAA's expected Kp for each 3-hour block, in UTC, starting after the latest block above. The dashed line is storm level, Kp 5. A forecast Kp is an outlook, not a measurement.
| UTC | Oct 6 | Oct 7 | Oct 8 |
|---|---|---|---|
| 00–03 | – | 2.67 | 1.33 |
| 03–06 | – | 2.67 | 1.67 |
| 06–09 | – | 2.33 | 1.33 |
| 09–12 | – | 2.00 | 1.67 |
| 12–15 | – | 1.67 | 1.67 |
| 15–18 | – | 1.67 | 1.33 |
| 18–21 | – | 2.00 | 1.33 |
| 21–00 | 2.67 | 2.00 | 1.33 |
Kp runs from 0 to 9. Storms start at Kp 5, where NOAA's G scale begins. The places listed are where aurora comes into range, low on the horizon, at about that Kp. Treat them as a guide, not a guarantee.
| Kp | NOAA level | In plain English | Aurora comes into range at about this Kp |
|---|---|---|---|
| Kp 0 | Quiet | Very calm. The auroral oval is a thin ring close to the magnetic poles. | Aurora comes into range for |
| Kp 1 | Quiet | Calm. Aurora stays at high latitudes and is often faint. | Aurora comes into range for |
| Kp 2Latest block | Quiet | Still quiet, with a little more movement. This is an ordinary night. | Aurora comes into range for |
| Kp 3 | Unsettled | Slightly disturbed. Displays at high latitudes tend to be brighter and more active. | Aurora comes into range for |
| Kp 4 | Active | Disturbed, one step short of a storm. The oval starts to extend toward lower latitudes. | Aurora comes into range for |
| Kp 5 | G1 minor storm | A minor storm. Weak power grid fluctuations and small effects on satellites are possible. | Aurora comes into range for |
| Kp 6 | G2 moderate storm | A moderate storm. Power systems at high latitudes can see voltage alarms and shortwave radio can fade. | Aurora comes into range for |
| Kp 7 | G3 strong storm | A strong storm. Power grids may need voltage corrections. Satellite navigation and shortwave radio can be intermittent. | Aurora comes into range for |
| Kp 8 | G4 severe storm | A severe storm. Widespread voltage control problems are possible and satellite navigation can be degraded for hours. | Aurora comes into range for |
| Kp 9 | G5 extreme storm | An extreme storm, the top of the scale. Power grids can have widespread problems and shortwave radio can be out for a day or more. | Aurora comes into range for |
The marked row is the latest 3-hour block, 18:00–21:00 UTC. Places in green are within reach at that Kp on a dark, clear night.
Kp reached storm level on 55 of 365 days.
The highest value was Kp 8.7 on November 12, 2025, a G4 severe storm.
Each UTC day is counted once, by its highest 3-hour Kp. These are GFZ's published values, which can differ slightly from NOAA's estimates in the charts above. Kp history from GFZ Potsdam (CC BY 4.0).
The Kp index is a number from 0 to 9 that describes how disturbed Earth's magnetic field was over a three-hour period, averaged across the planet. It is worked out from magnetometers at observatories around the world. Values below 3 are quiet, 3 is unsettled, 4 is active, and 5 or higher is a geomagnetic storm on NOAA's G scale, from G1 at Kp 5 to G5 at Kp 9.
Every three hours. The UTC day is split into eight blocks starting at 00:00, and the value for each block is published shortly after the block ends. This page checks NOAA for a new value every 15 minutes, and the line above the headline names the block the value belongs to.
It depends on your magnetic latitude, so there is no single number. Near the auroral oval, in places such as Tromsø and Fairbanks, aurora is within reach on quiet nights at Kp 0 to 2. At about Kp 5 it comes into range for places such as Seattle and Toronto. At about Kp 7 it comes into range for places such as New York City and London. These numbers are a guide, not a guarantee. You also need a dark, clear sky, and a strong substorm can bring aurora into range at a lower Kp than usual.
Kp summarises three hours and is published after the block ends, so the latest value describes conditions that are already up to a few hours old. It is also one number for the whole planet. Aurora can brighten and fade within minutes during a substorm while Kp barely moves. Kp tells you how far the auroral oval reaches, not where the aurora sits in your sky at a given moment. For conditions minute by minute, the solar wind and magnetometer readings respond faster.
243 places, each with the Kp at which aurora comes into range there, tonight's cloud cover and hours of darkness.
GOES magnetometer readings alongside the Kp charts, for a closer look at how the field is behaving.
NOAA's full outlook, with the chance of radio blackouts and radiation storms as well as Kp.
Source: NOAA SWPC planetary K-index and Kp forecast, checked every 15 minutes. Kp history from GFZ Potsdam (CC BY 4.0)
