This Wireless Pool Thermometer from La Crosse is pretty darned good

January 3, 2025

I bought this La Crosse wireless pool thermometer for $51.09 on Amazon back in early October, brought it home, and tossed it into my pool. That was only about three months ago, but it has worked flawlessly since then.

The specific model number on my Amazon purchase was 331-09667-INT. I'm not sure what the 'INT' means. (Introductory, maybe?) An apparently identical product sells on the La Crosse website under the model number 331-09667V2 for about ten bucks more. But there's no difference between the two that I can discern.

Plenty of range, long battery life

My pool is about 80 feet from the spot inside my house where the remote display sits. The remote display has a little bar graph that shows signal strength on a scale of one bar to five. At 80 feet, with an exterior masonry wall between it and the pool thermometer, it shows five bars.

Unfortunately, there is no indicator on the remote display to show the battery condition of the transmitting unit. That would have been a nice feature. But three months along, the two disposable 'AA' batteries are powering the unit just fine.

I was initially concerned about the LCD screen on the transmitting unit. LCD screens constantly exposed to direct sun never do well over the long haul, and I'll be surprised if this one is still readable a year from now. But as long as it continues to transmit, I'm not going to worry about its display. It's nice being able to glance at it while walking past the pool and be able to see the temp, but the main reason I wanted this was so I could see the pool temp from inside the house.

Transmits on 914.9MHz, can be made to work with Home Assistant

My favorite thing about this wireless thermometer is I can pull its data into my Home Assistant instance. Achieving this took some tinkering: I used an RTL-SDR dongle, plus Benjamin Larsson's awesome RTL_433 program, to capture the thermometer's signal and output it to my local network as MQTT. I also used this great Home Assistant Add-on for RTL_433 users that automatically discovers sensor data in the MQTT stream, making the data easy to use in your integrations. I'll try to write more on how to do this as soon as I get the chance.