Bit late (don't monitor a lot) but I have been doing this (via MQTT) for about a year now. HA has native MQTT support (which I also used for other things). To set it up you need:
1. MQTT Broker. There are some publicly available but I use mosquitto on the mac via homebrew to keep my system entirely behind my firewall.
2. Set up the weather cat "scraping" via AppleScript. Mine is based on mangrovemikes but is now very stable. You can find at
https://github.com/mikethefarmer/WeatherCatMosquittoBridge. There are a couple of lines that need configuring at the top for your setup.
3. Install MQTT add-on in HA.
4. Setup MQTT sensors in HA.
I have attached an extract of my Weathercat sensors definition. Note that there is no "sensors" section header, as I have mine in a separate sensors.yaml file (good idea as I have pages of MQTT sensors - you wouldn't be able to jump over them if all in config.yaml!). There are quite a lot as I have a second Temp/Hum unit together with a soil moisture unit, so you may not need quite so many. The MQTT topic "base" and broker address as set in the applescript.
I also tend to run a terminal window subscribing to all my MQTT topics to keep an eye on the broker. Just use
mosquitto_sub -h localhost -v -t "#" to subscribe to all
I have promised to write an MQTT section of the wiki, just been far too busy just yet.
I also have an AppleScript to get external MQTT into WeatherCat as a synthetic channel - it described in another post somewhere in this section (about a year ago?).
R, Mike