Kp index now
The planetary K index measures how disturbed Earth's magnetic field is, from 0 (calm) to 9 (extreme storm). The higher it goes, the farther from the pole the aurora reaches.
Last official 3-hour value, Oct 25, 3:00 AM UTC. NOAA SWPC.
Last 3 days and the next 3
Where each Kp level reaches
Our estimate for the aurora low on the northern horizon, by eye, from a dark place. A phone camera often catches it one level lower.
| Kp | NOAA scale | Examples of places that need about this level |
|---|---|---|
| 1 | quiet | Fairbanks, AK, Anchorage, AK, Nome, AK |
| 2 | quiet | Juneau, AK |
| 3 | quiet | Ketchikan, AK |
| 4 | active | Presque Isle, ME, Marquette, MI, International Falls, MN, Havre, MT, Minot, ND, Duluth, MN |
| 5 | G1 | Sandpoint, ID, Berlin, NH, Plattsburgh, NY, Aberdeen, SD, Newport, VT, Bellingham, WA |
| 6 | G2 | Torrington, CT, Rockford, IL, Mason City, IA, Gloucester, MA, Astoria, OR, Erie, PA |
| 7 | G3 | Wilmington, DE, South Bend, IN, Hagerstown, MD, Kirksville, MO, Valentine, NE, Newton, NJ |
| 8 | G4 | Fort Collins, CO, Hays, KS, Covington, KY, Winnemucca, NV, Logan, UT, Winchester, VA |
| 9 | G5 | Bentonville, AR, Redding, CA, Boone, NC, Woodward, OK, Kingsport, TN, Nashville, TN |
See every state with its level on northern lights by state.
The NOAA G scale
| Level | Kp | Name | Aurora (NOAA description, simplified) |
|---|---|---|---|
| G1 | 5 | Minor | Often seen at high latitudes, such as northern Michigan and Maine |
| G2 | 6 | Moderate | Can reach New York and Idaho |
| G3 | 7 | Strong | Can reach Illinois and Oregon |
| G4 | 8 | Severe | Can reach Alabama and northern California |
| G5 | 9 | Extreme | Can be seen as far south as Florida and southern Texas |
Questions people ask
What is a good Kp for seeing the northern lights?
It depends on where you are. In Alaska, Kp 1 to 3 is often enough. Along the Canadian border, Kp 4 to 5. In the middle of the US, Kp 6 to 7, and in the South only Kp 8 to 9 storms bring it.
How often is Kp updated?
NOAA publishes an estimated Kp every minute and the official planetary Kp for each 3-hour block of the day (00-03 UTC and so on). Final values come later from GFZ in Germany.
Is a high Kp a guarantee?
No. Kp is an average over 3 hours and the whole planet. The aurora can flare up and fade within minutes, and clouds or moonlight can hide it.
Source: NOAA Space Weather Prediction Center, planetary K index and 3-day Kp forecast (public domain). Our feed refreshes every 5 minutes. Unofficial copy for general information.
Page built: October 25, 2026.