SwitchBot WiFi Thermometer Hygrometer 3 Pack with Hub Mini, IP65 Indoor Outdoor Thermometer Wireless, Humidity/Temperature/Dewpoint/VPD/Absolute Humidity Sensor with Smart Alerts, Works with Alexa

While these are larger than some other temperature/humidity sensors it means that the batteries will need replacing far less frequently than devices that use coin cells and rechargable AAAs can also be used. The IP65 rating means that they can stand a bit of moisture and can be used outdoors or in a kitchen freezer but they are not fully waterproof so don't put them in your fish tank for example. They transmit readings via BLE advertisement every couple of seconds and I have one in the shed at the bottom of the garden and can pick up its signals from the lounge which is well over 25m away with a couple of brick walls between them. The SwitchBot app can talk to them directly over Bluetooth/BLE or you can use any of SwitchBot's BLE/WiFi hub-capable devices to connect them to your SwitchBot account and access them from anywhere.From a Home Assistant server equipped with a Bluetooth radio, the local SwitchBot BLE integration also works well and you can use an ESPHome-based BLE/WiFi bridge node with the SwitchBot integration if the server is out of BLE range. Alternatively, the author of the Smart Home Scene web site has reverse-engineered the BLE announcements allowing you to use an ESPHome (or other tinkerer platform) device to expose the sensors directly to Home Assistant or whatever system you use. I use this approach as the ESPHome BLE repeater can be a bit flakey between my multiple VPN-connected sites whereas exposing the sensors via the ESPHome WiFi integration is much more reliable.The sensor is pretty accurate out of the box but you can use the app to calibrate the temperature readings using an ice bath and SwitchBot provide step-by-step instructions for doing this.

Really all I needed was a replacement for a simple, broken outdoor thermometer but I saw these SwitchBot devices on Amazon at a very affordable price. Even more affordably you can get a box of three for around £20 so I went for this option. They come with AAA batteries pre-installed (estimated lifetime 2 years) and a specified operating temperature of -20C to 60c although ‘best between 5C and 50C’. The instruction manual was probably designed for the Queen’s Dolls’ House but is fairly easy to follow with a Q code for setting up the app on iOS or Android. Connectivity is via Bluetooth which should provide adequate coverage but needs a bit of experimentation if, like me, you have an old house with very solid walls.So why a ‘weather geek’? Well what I didn’t appreciate when I bought the devices was the remarkable amount of data they not only provide but also store. They measure temperature and humidity about every 15 minutes and store these measurements internally so that on your phone you can get the current readings immediately for all thermometers or within a second or two your can see on a graph how the measurements have changed over the past hour, day, week or year. These data can also be exported as csv files. I haven’t tried that at yet - and probably won’t. Even mor geeky the devices compute and display such things as Dew Point and Vapour-pressure Deficit which can be a gripping topic at any dinner table.Better still for the real geek, a few more pounds will buy a SwitchBot Hub Mini which puts the Bluetooth readings onto your server so that they can be viewed remotely: handy if you can also control your Central Heating remotely, as I am able to do although not via one of the many SwitchBot additional tools.

For me, this is a 5* product. I’ll get into why after I explain the 4*. One of the indoor / outdoor sensors in my pack of three unfortunately failed its firmware update out of the box and became bricked. Thankfully, support have been amazing and sending me a replacement. The process was little hassle. That being said, I feel out of principle I cannot give a 5* right now.The product itself is brilliant. Compact (actually smaller than I was expecting), which makes it unobtrusive and good to put in tighter spots or even inside things (a terrarium for example). Connectivity is excellent. No hub or even an app are needed for this, you can hook it straight into home assistant over bluetooth. However, the switchbot app is great and has a lot of useful functionality. One of my favourite things about this is that you can just use it or take it with you anywhere and check temp and humidity on your phone. I’m a bit of a data nerd so i’ve taken it to all sorts of different places in the short time i’ve had it.Accuracy is hard to gauge without a benchmark I know is 100%, which i don’t have. But I believe they are very accurate, and did my research before hand to make sure they would be. Having a number of these sensors, they seem to agree strongly with one another. Which is reassuring. The one thing I will mention, is that their time to adapt to a drastic change in temperature +-20 celsius is quite long. Perhaps 20 mins or maybe a bit more. This is no issue, as the accuracy is stellar. But for some others this may be a concern.Overall, i’d highly recommend these.

Very pleased with these temp & humidity sensors. Great that the data is viewed on the phone where I want it. They feel of very good quality, look nice, and are conveniently small.With the three-pack I bought, one of them wouldn’t update the software (several tries, the update got stuck part way through, then a “failed” message displayed), so I deleted it from the SwitchBot app and added again to the app, and it then updated with no problems. The other two updated perfectly first try.I keep one in the car, it is interesting to see the track of the range of temperatures in such an environment. Others are around the house. Bluetooth connection is ok, but of course is sensitive to walls etc being in the way. It would be handy to have one in the greenhouse - something I may look to do.