[coffeecheque]

Have you thought about using devices like the ESP8266? [1]

You could probably work out a way to wire in the humidity sensor onto that, and scale it up via a printed PCB.

And instead of worrying about GETs, you can program the device to report in via MQTT to a central server.

You likely know all this, just curious :)

[1] https://www.sparkfun.com/products/13678