SpaceWeatherTracker · NOAA sources
What Is the Kp Index?
Kp is a planetary index of geomagnetic disturbance derived from ground-based magnetic observations. It runs from 0 to 9 and is reported in three-hour intervals; it is not a direct measurement of aurora brightness.
Latest geomagnetic reading
Kp 3.0
Below geomagnetic storm threshold
NOAA interval begins
Kp summarizes a three-hour interval. The page checks sources every five minutes; that is not NOAA's observation cadence.
What Kp measures
Kp combines standardized local K-indices from a network of geomagnetic observatories. It summarizes global magnetic disturbance rather than conditions at a single observing site.
Kp and the storm scale
NOAA’s geomagnetic scale associates Kp 5 with G1, 6 with G2, 7 with G3, 8 with G4 and 9 with G5. Values below the storm threshold are not G-scale storms; G0 is not an official NOAA storm category.
Why Kp does not guarantee aurora
Magnetic latitude, local time, solar wind conditions, clouds, moonlight and light pollution influence what you can see. Aurora can be visible at high latitudes even when global Kp is low.
Observed versus forecast Kp
Observed and estimated indices describe a reporting interval. Forecast Kp is a prediction. The observation timestamp should not be replaced by the time this page was refreshed.
Recent NOAA notices
All notices and validity detailswarning
Kp 4 Geomagnetic Activity Warning
Issued
NOAA product text
Space Weather Message Code: WARK04 Serial Number: 5435 Issue Time: 2026 Oct 13 2058 UTC EXTENDED WARNING: Geomagnetic K-index of 4 expected Extension to Serial Number: 5434 Valid From: 2026 Oct 13 0115 UTC Now Valid Until: 2026 Oct 14 1200 UTC Warning Condition: Persistence NOAA Space Weather Scale descriptions can be found at www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude. Induced Currents - Weak power grid fluctuations can occur. Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.
warning
Kp 4 Geomagnetic Activity Warning
Issued
NOAA product text
Space Weather Message Code: WARK04 Serial Number: 5434 Issue Time: 2026 Oct 13 1431 UTC EXTENDED WARNING: Geomagnetic K-index of 4 expected Extension to Serial Number: 5433 Valid From: 2026 Oct 13 0115 UTC Now Valid Until: 2026 Oct 13 2100 UTC Warning Condition: Persistence NOAA Space Weather Scale descriptions can be found at www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude. Induced Currents - Weak power grid fluctuations can occur. Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.
warning
Kp 4 Geomagnetic Activity Warning
Issued · Valid to 2026-10-13T15:00:00.000Z
NOAA product text
Space Weather Message Code: WARK04 Serial Number: 5433 Issue Time: 2026 Oct 13 0115 UTC WARNING: Geomagnetic K-index of 4 expected Valid From: 2026 Oct 13 0115 UTC Valid To: 2026 Oct 13 1500 UTC Warning Conditions: Onset Comment: NOAA Space Weather Scale descriptions can be found at www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude. Induced Currents - Weak power grid fluctuations can occur. Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.
watch · G1
G1 Geomagnetic Storm Watch
Issued
NOAA product text
Space Weather Message Code: WATA20 Serial Number: 1129 Issue Time: 2026 Oct 11 1911 UTC WATCH: Geomagnetic Storm Category G1 Predicted Highest Storm Level Predicted by Day: Oct 12: None (Below G1) Oct 13: G1 (Minor) Oct 14: None (Below G1) THIS SUPERSEDES ANY/ALL PRIOR WATCHES IN EFFECT Comment: NOAA Space Weather Scale descriptions can be found at www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude. Induced Currents - Weak power grid fluctuations can occur. Spacecraft - Minor impact on satellite operations possible. Aurora - Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.
cancelled · G2
G2 Geomagnetic Storm Cancelled
Issued
NOAA product text
Space Weather Message Code: WATA30 Serial Number: 286 Issue Time: 2026 Oct 11 1702 UTC CANCEL WATCH: Geomagnetic Storm Category G2 Predicted Cancel Serial Number: 285 Original Issue Time: 2026 Oct 09 1636 UTC Cancelled Level Predicted: Oct 11 : None (Below G1) Conditions no longer warrant a G2 Watch. NOAA Space Weather Scale descriptions can be found at www.swpc.noaa.gov/noaa-scales-explanation Potential Impacts: Area of impact primarily poleward of 55 degrees Geomagnetic Latitude. Induced Currents - Power grid fluctuations can occur. High-latitude power systems may experience voltage alarms. Spacecraft - Satellite orientation irregularities may occur; increased drag on low Earth-orbit satellites is possible. Radio - HF (high frequency) radio propagation can fade at higher latitudes. Aurora - Aurora may be seen as low as New York to Wisconsin to Washington state.
Recent products can include expired, superseded or cancelled notices. Read the original product before treating it as an active warning.
Sources and limitations
Independent interpretation by SpaceWeatherTracker; official measurements and notices are attributed to NOAA. Not for safety-of-life or operational decisions.