Due to heavy fire smoke in the area, we recently needed a way to monitor the outside air quality. Amongst the few devices that caught our eye, the Netatmo Smart Home Weather Station stood out as a decent compromise between features and price.

Until it turns out half the features (including outside air quality) aren’t measured locally, and instead obtained from other data sources.

Product review

Pros

• Fancy compact design
• Supported in Home Assistant
• CO2 monitoring inside

Cons

• Inside module needs USB power
• Cloud-dependent (no local access as far as I could see)
• Doesn’t actually measure any outside air quality

What is measured locally?

The Smart Home Weather station (inside module) measures temperature, humidity and pressure, as well as CO2 and noise levels. The Smart Outdoor Module measures temperature and humidity, as well as… no, that’s it, that’s the only two things the outside module measures locally. The additional information (weather, pollutant, …) made available from the website and the app comes from various sources, but not from the station itself.

So I made a corrected version of the marketing material available on the front page.

I didn’t realise this immediately, and only started investigating when I noticed that the main pollutant, according to the outside module, was exactly at the same level inside and outside of the house. I confirmed this with the customer support service.

tl;dr: Is the Netatmo Smart Weather Station with the Outdoor module equipped with its own air-quality measurement module?

I just bought the Netatmo Smart Weather Station with the Outdoor module. My main purpose is to accurately measure the air quality very locally in my garden.

Using the app, however, I am starting to suspect that the outdoors module does not actually measure the air quality itself, and is only limited to temperature and humidity.

Digging a bit more, and looking at the request/responses exchanged between the web dashboard and the servers, I further see requests to https://app.netatmo.net/api/simplifiedfuturemeasure. It returns a JSON object containing airqdata and airqdatav2. Both of those objects are noted as sourced from the EPA, and not from the hardware I just bought. The values in those fields matches exactly what the web dashboard display.

The answer confirmed my suspicions.

You will find on our site the functionalities and technical specifications of the station and its external module.
The outdoor module measures temperature and humidity.
The rest of the measurements are made by the Weather Station.

The weather forecast as well as the outdoor air quality are provided by a data provider.
These measurements require heavy equipment to handle all types of outdoor pollutants, a “simple” small outdoor module is unable to do so.

Following the advice, I checked the detailed specifications. There is indeed nothing in the way of air-quality sensing on the Outdoor Module. This is very much at odds with the bold communication on the front page. This is also disappointing when, at $250, the modules do barely more than much simpler, yet effective, Aquara climate sensors (affiliate link).

I ended up replacing it with a Davis AirLink sensor (affiliate link; also discussed, amongst others, in another review).