What you need
- Multimeter for macOS 13 or later, $19.99 once.
- The direct download version of Multimeter from this site (the Script source isn’t in the Mac App Store version).
jqfor picking numbers out of JSON. It comes with macOS 15 and later; on macOS 13 or 14 runbrew install jq.
Set it up
- Check it in Terminal. NOAA’s list is oldest first, so jq takes the last entry:Command
curl -s -m 8 https://services.swpc.noaa.gov/json/planetary_k_index_1m.json | jq '.[-1].estimated_kp' - Add a Script meter with the command, refreshing every 5 minutes.
- Range 0 to 9. Alerts on High values at the Kp for your latitude: about 5 for the northern US and UK, 7 for the middle of the US. Turn on the notification.
Multimeter settings
In Customize This Meter… (from the meter’s menu):
| Setting | Value |
|---|---|
| Source | Script |
| Command | curl -s -m 8 https://services.swpc.noaa.gov/json/planetary_k_index_1m.json | jq '.[-1].estimated_kp' |
| Refresh every | 5 minutes |
| Range | 0 to 9 |
| Alerts | High values: warning 5, critical 7, notify on critical |
| Label | KP |
| Face | Signal Bars, Heat Strip or Needle Gauge |
Tested: Run on October 29, 2026: 0 (a quiet day), in under a second.
Script meters need the direct download version of Multimeter from this site, which is the one on sale now. How commands run, the PATH they see and the 10 second limit are in the Script meters guide.
Limits
- This is the estimated planetary Kp, a global average. Local conditions, clouds and darkness decide what you see.
Troubleshooting
| Symptom | Cause | Fix |
|---|---|---|
| The script didn’t print a number | The command failed or printed an error message instead. | Run the exact command in Terminal. If it works there, check for tools that live outside the meter’s PATH and use their full path (which tool). |
| The script took longer than 10 seconds | A slow network call. Multimeter stops scripts after 10 seconds. | Keep the -m timeout on curl, and refresh less often. |
| Scripts need the version from multimeterapp.com | This copy of Multimeter came from the Mac App Store, which can’t run scripts. | Use the direct download version, or run the command from cron or launchd and point a File meter at its output. |
Questions
Does this work in the Mac App Store version?
Script meters need the direct download version from multimeterapp.com, because the App Store sandbox doesn’t let apps run your commands. Web Address, File and Sent Value meters work in every version.
What Kp do I need to see the aurora?
Roughly: Kp 3 to 4 for Alaska, northern Canada and Scandinavia; 5 (a G1 storm) for the northern US border and Scotland; 7 and up for the middle of the US and southern England.