Range
Kp 0 is very quiet and Kp 9 is extremely disturbed.
Geomagnetic index · 0 to 9
Kp Index
See the current planetary Kp reading and understand its 0–9 scale, three-hour cadence, NOAA storm threshold, and limits for local aurora viewing.
Direct answer
Kp is a global, planetary index summarizing geomagnetic disturbance in three-hour intervals. Values run from 0 to 9; NOAA geomagnetic storm conditions begin at Kp 5, but a single current Kp value is not a city-level aurora forecast.
Storm threshold
NOAA G-scale geomagnetic storms begin at Kp 5.
Time resolution
Kp represents a three-hour planetary interval rather than an instantaneous reading at one magnetometer.
Physical space weather · refreshes hourly
The Sun–Earth Weather Dial
Current instrument readings with their observation time. No personal, medical, or spiritual state is inferred.
Kp is planetary context, not a local aurora forecast. GOES X-ray class is not a geomagnetic-storm forecast. Use the linked NOAA products for operational decisions.
What Kp summarizes
Kp combines standardized disturbance measurements from a network of mid-latitude geomagnetic observatories into a planetary index. It is valuable because one number offers a broad view of global geomagnetic activity. That compression also removes local detail, so Kp should be read as context rather than a direct measurement over the user’s town.
From quiet to storming
Low values generally correspond to quiet geomagnetic conditions. Kp 4 is active or unsettled but below NOAA’s G1 storm threshold. Kp 5 corresponds to G1, and higher Kp supports higher G levels through G5 at the extreme end. The exact operational impact language should come from NOAA’s scale, not from invented emotional adjectives.
Kp and aurora
Stronger geomagnetic disturbance can expand the auroral oval toward lower geomagnetic latitudes. Yet visibility still depends on where the oval is at the relevant time, local darkness, cloud, moonlight, and a clear poleward horizon. Camera sensors may record color where unaided eyes see only a faint pale arc.
Nowcast, forecast, and final index
A live product may be a recent estimate or nowcast, while later processing can produce a definitive value. Forecasts describe possible future conditions and carry uncertainty. Always retain the product timestamp and label; do not present today’s observation as a guarantee for tonight or tomorrow.
Responsible use
Kp matters to aurora observers and to professionals concerned with satellites, navigation, radio, and power systems. For operational decisions, follow official alerts and procedures. The index does not diagnose headaches, sleep changes, anxiety, or spiritual states, and this almanac does not attach a medical conclusion to it.
Sources and live-data notes
- NOAA SWPC: Planetary K-index ↗The planetary Kp product used by the Almanac space-weather endpoint.
- NOAA SWPC: Space Weather Scales ↗Official R, S, and G scale meanings and impacts.
- NOAA SWPC: Aurora Dashboard ↗Forecast imagery and official aurora context; a global Kp value alone is not a local forecast.
- The Great Almanac live APISame-origin gateway for the latest NOAA-derived Kp and GOES X-ray reading.
Continue through the Sky & Time Almanac
Cluster hubSky & Time AlmanacAll observation guides, live instruments, and source boundaries.
NOAA observations · physical Sun–Earth systemSpace WeatherRead the current planetary Kp index and GOES X-ray class, then understand what NOAA space-weather scales do and do not say.
Northern and southern lightsAuroraUse current Kp as context, then learn why aurora visibility requires an oval forecast, darkness, weather, geomagnetic latitude, and a clear horizon.
Magnetosphere · NOAA G scaleGeomagnetic StormsUnderstand NOAA’s G1–G5 geomagnetic storm scale, its Kp relationship, possible technology effects, and why current Kp is not a future local forecast.
GOES soft X-rays · A through XSolar FlaresSee the latest GOES soft X-ray class and learn how A, B, C, M, and X flare classes differ from CMEs, geomagnetic storms, and radio-blackout scales.
Common questions
What Kp value counts as a geomagnetic storm?
NOAA’s G scale begins at Kp 5 for G1 conditions. Kp 4 is active but below that storm threshold.
Is Kp measured in real time?
Products may provide recent estimates, but Kp is defined for three-hour intervals and definitive values can be processed later. Check the product label and timestamp.
What Kp do I need for aurora?
There is no universal city threshold. Geomagnetic latitude, auroral oval position, darkness, cloud, Moon, and horizon all matter.
