I haven't released the code for it yet, but there are plenty of tutorials online. It's using NodeMCU and a DHT11. If there's more interest in hacking the device, I can provide some blogposts or tutorial videos.
There are 5 available and 15-25 more are on the way. Please contact me if you're interested. I'm planning on selling it for around $35 and for the first few batches at $30 (as an early adopter discount). Email: antoniuschan99@gmail.com
For personal uses, I have a waterproof temperature sensor coming in, and plan to use that for my aquarium, so maybe I will produce that version. Also I am tinkering with electrical outlets that can be remotely triggered. So you can set the weather alarm to trigger appliances.
Monitor the temperature in my office (I run a few servers)
Check the temperature outside. I'm close enough to a major city that everything uses that location, but often it's different from where I'm actually at.
My garage. Sometimes I have paints/stains/beer/etc that shouldn't be above/below a certain temperature.
https://www.facebook.com/kokonautweathersensors/
It's not using my network, but it's hackable enough that you can use it on your own network if you know how to flash it yourself.