The indoor and outdoor readings are mixed with local weather data from a nearby station that provides precipitation information and a forecast. What's fascinating is that Netatmo is using your data to create the Urban Weather program, a project in which a hopefully huge number of Netatmo sensors will generate a worldwide database of weather and air quality information. You can opt out of the Urban Weather program if you don't want that information shared.
Setup of the devices is a piece of cake. Upon opening the box, you attach the indoor sensor to your Mac or PC using an included USB cable, then go to a Netatmo website to get setup software. About the only thing you really need to do is make sure that the indoor sensor has your Wi-Fi password, and then you can unplug it and place it elsewhere in your house. The outdoor sensor runs off of four AAA batteries (included), and does not require setup.
All of the information gathered by the sensors is visible to you in an iPhone app. The Netatmo website shows what appears to be a universal version of the app running on an iPad, but as of the time this review was being written, the app only ran in 2X mode on the iPad and didn't look that great on an iPad Retina display.
As for the iPhone app, it looks amazing. You have your choice of three views, chosen by swiping up and down the screen. The first view is an overview of existing inside and outside conditions. An icon shows the current weather outside, with readings for temperature and humidity, and a calculated "feels like" temperature.
There's also an indication of outside air quality. If you wish to see what's causing your air quality to be less than perfect, a tap on the "car" icon brings up a listing from a local pollution monitor. In the case you see here, ozone pollution was apparently an issue, although that monitor is most likely in downtown Denver 16 miles away. At our elevation about 500 feet above downtown, there usually isn't as much of an ozone problem.
One of the other views shows only the inside readings, complete with a reading of the existing CO2 levels in the house or office and an indication of just how noisy it is in your place. That green "fuzzball" indicates that things are rather nice in my office -- the temperature is reasonable, the CO2 level isn't toxic, and it's fairly quiet. If I was in an air conditioned office in a smoggy town with a lot of traffic noise, that ball might be yellow or red. The final view shows outdoor weather conditions, those taken from both the outdoor sensor and a local weather station.
As for location of the sensors, I put the indoor sensor on a table near my "iPad charging station" and the outdoor sensor was installed in a protected location on a wall where it's out of direct sun and rain. I'd love to test the Netatmo outdoor sensor over a long period of time to see how it survives the cold temperatures of winter.
How's the accuracy? That's something I'm really not sure about, since the readings were not what I expected for humidity. Colorado is a very dry environment, and it's not unusual for us to see humidity in the range of 20% or less most of the year. Today there was a chance of rain, and a local weather station showed 40% humidity. The indoor monitor showed 54% humidity, quite a bit higher. That might be accurate due to the proximity to things like a bathroom, kitchen, and laundry room.
After a few days of following the readings, I noticed that the humidity never seemed to drop below about 40%, while the National Weather Service readings showed about 31%. That pointed out something to me -- the impact that my lawn and trees have on raising the humidity at my house.
You'll also want to make sure you wait an hour or two for the readings to settle down. Initially, the barometric reading was showing 24.04 inHg, which is ridiculously low. It stayed there for a while, then suddenly popped up to a more reasonable -- and completely accurate -- 30.05 inHg.
Looking at historical data using the app is quite simple; you just tip the iPhone over into landscape mode and a chart appears. You can select from temperature, humidity, pressure, CO2 level, and sound meter readings from the inside sensor, and temperature and humidity from the outside sensor. Scrolling the data back and forth over a read line tells you what the specific reading was for a particular time, and you can pinch or reverse-pinch to see less or more detail.
While it's not a traditional weather station, I think a lot of iPhone owners will find the Netatmo personal weather station to be right for them. It's easy to set up, and provides information to you on your personal comfort that you may not otherwise think about.
Easy to set up
Attractive and not out of place in any modern household
Captures both indoor and outdoor temperature and humidity; provides readings of CO2 and sound levels for indoor
Relatively inexpensive compared to more sophisticated weather stations available from Oregon Scientific and similar companies
iPhone app provides comfort level readings at a glance
Doesn't provide outdoor wind velocity or precipitation readings, which may be important to some potential buyers
App is not universal; runs in 2X mode on iPad
Who is it for?
Anyone who wants to keep track of weather at their location but doesn't want to install and manage a complicated weather station.