Here is a drawing of a remote temperature alarm you can make yourself.
You need a rain bird rain/freeze sensor a 24VAC relay a 3 way switch and a 24VAC buzzer/light.
Some wire a terminal block and a box to put it all in.
I think I got the wiring right.
COM=common.
NC= normally closed.
NO= normally open.
Feel free to ask any questions and for sources of the things you will need.
Remote Temp Sensor r.jpg