What you need
- Multimeter for macOS 13 or later, $19.99 once.
- Your latitude and longitude.
Set it up
- Find your latitude and longitude. Open-Meteo’s place search gives them for any town (the first result’s
latitudeandlongitude):Terminalcurl -s 'https://geocoding-api.open-meteo.com/v1/search?name=Plano&count=1' - Add a Web Address meter with this address and the key path
current.us_aqi:Web addresshttps://air-quality-api.open-meteo.com/v1/air-quality?latitude=33.02&longitude=-96.70¤t=us_aqi - Refresh every 15 minutes. Range 0 to 200; alerts on High values at 100 (unhealthy for sensitive groups) and 150 (unhealthy).
Multimeter settings
In Customize This Meter… (from the meter’s menu):
| Setting | Value |
|---|---|
| Source | Web Address |
| Web address | https://air-quality-api.open-meteo.com/v1/air-quality?latitude=LAT&longitude=LON¤t=us_aqi |
| Key path | current.us_aqi |
| Refresh every | 15 minutes |
| Range | 0 to 200 |
| Alerts | High values: warning 100, critical 150 |
| Label | AQI |
| Face | Gradient Track, Mood or Plant |
Tested: Run on October 29, 2026 for Plano, Texas: US AQI 53, PM2.5 7.9 µg/m³; Berlin: European AQI 50.
More on this source, including every format it reads, in the Web Address guide.
Limits
- Open-Meteo allows up to 10,000 calls a day for non-commercial use without a key; one meter every 15 minutes uses 96. Its models update about every hour.
- These are modeled values for your coordinates, not a sensor on your street.
Variations
European AQI
Use current=european_aqi and the key path current.european_aqi. Alerts at 60 and 80.
PM2.5 in µg/m³
current=pm2_5, key path current.pm2_5. The WHO daily guideline is 15.
Pollen (Europe)
current=grass_pollen (or birch_pollen, ragweed_pollen), grains per m³. Open-Meteo’s pollen data covers Europe only.
Troubleshooting
| Symptom | Cause | Fix |
|---|---|---|
| No number found in the response | The key path doesn’t match the reply. | Run curl -s with the address and read the JSON. Dots walk into objects, numbers pick array items (items.0.count). |
| Couldn’t reach the address | No network, a typo in the host, or the service is down. | Open the address in your browser. Multimeter tries again at the next refresh. |
Questions
What do the AQI numbers mean?
US AQI: 0 to 50 good, 51 to 100 moderate, 101 to 150 unhealthy for sensitive groups, 151 to 200 unhealthy, above 200 very unhealthy.