No Rain Sensor Tripped ; Not HomeKit Compatible?!

I just installed this week and a few things have me ready to send this unit back:

#1) The rain sensor that I connected doesn’t appear to be tripping, even though it’s been raining here for 4 days non stop. Please see the JSON reply below

      'model': 'GENERATION3_4ZONE',
      'scheduleModeType': 'MANUAL',
      'deleted': False,
      'rainSensorTripped': False,
      'utcOffset': -14400000,
      'homeKitCompatible': False

#2) When I ordered this unit I was told by the sales person that I could use HomeKit to integrate with my existing Home Automation. Clearly as you can see above that this version is not HomeKit Compatible. Is there a firmware update I can install to enable this?

Here’s the wiring to show how I connected the Rain Sensor. Maybe I did something incorrect?

What kind of sensor did you get? Did you enable it in the app?

I have a Rain Bird SMT rain sensor which I read on this community “should work”. I have enabled it in the app:

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Hmmm, it is not listed at Rain Sensors FAQ ( (only shows the WR2), but a incomplete article is at Rachio compatibility with RAIN BIRD ESP-SMT Weather Sensor

I see it is talked about Rainbird SMT Weather Sensor, Gen 3 controller and Flex Daily - Getting Started / Rachio 3 - Rachio Community and it looks like you hooked up accordingly and it does not seem to be working in that case. Another one: Rain Bird SMT Rain Sensor Compatible? - Accessories & Sensors / Rain Sensors - Rachio Community.

I am not finding a posting that says that it will work, would you mind posting that please?

@ryanbuckner - Rachio gave up on Homekit integration back in September. See →

If the Rain Bird sensor is the one that reports temperature, humidity, etc. in addition to rainfall then it is not compatible with Rachio. Rachio only works with a binary sensor - open or closed.

If you’re unsure of the rain sensor, post a picture of the sensor and any label.

This one sounds like it’s on me. A “smart” irrigation system that is not compatible with home automation… Maybe I should have done more homework.

Either way - here are some pictures of the Rain Bird SMT sensor. It’s a binary switch, not with other features.

Is it just two wires? If so and you have a multimeter, can you hook it up to the two wires to measure the resistance and then measure again when water is going through it carefully?

@ryanbuckner - I believe that Rain Bird sensor sends serial data (e.g. temperature and rain) down the two wires in a proprietary format for Rain Bird’s controller to use. Rachio can’t use that data or sensor.


I would agree with @DLane. I took a fairly quick scan through the manual, man_ESPSMT_en.pdf (, and it does seem to provide more than a simple rain sensor. I see (both are part of the sensor mounted outside:

  • All irrigation will be suspended to prevent potential freeze damage to the irrigation components if the measured temperature is below a user set level.
  • The rain gauge not only acts as a rain shut-off device, it also provides rainfall intensity and accumulation information to the controller in order to prevent overirrigation by accounting for “effective” rainfall.

So, measuring the resistance would be futile.

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Thanks everyone. I’ll disconnect it.

I use a Tempest weather station which beautifully integrates with my Rachio 2nd Generation.

Plus the weather station is really nice to have for all the other uses I have for it.

You could extend the existing mount for your Rain Bird and install it there and it is solar powered and totally wireless to the base station, which you can tuck away anywhere you can plug it in and it connects to your wifi.

To be fair, some people have no issues at all with HomeKit. It has something to do with everyone’s individual network and a few other things it seems.

Update to the latest firmware and see if you can get it working.

As for the sensor, for short term turn on the weather intelligence and choose the closest working weather station to grab info from. I say closest working because some don’t actually collect rain data which I found out when my sprinklers went on after a heavy rain. Changed to another and all has been good.

Thanks for the reply. My firmware is iro3-firmware-hk-5-640 which appears to be the latest. Anything else I can do to troubleshoot the network or my setup?

I have chosen the closest working weather station to the house and this appear to be working properly to plan for forecasted rain. What is cannot do (and I’ve seen this issue with other posts here) is determine when it’s actually raining. I haven’t had these issues but others have, and I want to avoid:

  • On days that rain is forecasted but it never rains, the Rachio skips cycles incorrectly. for others
  • On days that rain is not forecasted but it rains, the Rachio waters incorrectly. Again, for others. I haven’t had this problem yet since rain has been forecasted in Northern VA since I installed over a week ago

I may consider purchasing a rain sensor that is compatible. I don’t expect the weather forecasts to be accurate enough, since others have pointed this out.

UPDATE: I was able to get HK to connect to the Rachio by trying some tips on an old blog. I also disconnected the rain sensor and got a note “Rain Sensor Tripped, schedule will be suspended”

So we’ll see how it goes. Thanks for all your help

When do you have your system watering during the day? I believe it pulls everything at the end of each day so if you water early in the morning it’s got a better chance to be more accurate than at the end of the day…

Also it never actually skips a cycle. It simply waits longer to run it, so in theory if it gets new data the next night that it didn’t actually rain that day it should then run the following day since it now knows it wasn’t actually watered and it’s moisture level was not filled …. So watch for that and see how it does with that.

Of course I’m assuming you have days between watering zones and that your system doesn’t water daily…

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I’m using a Flex Daily schedule set to complete before sunrise. Today was the first day in 10 days forecasted without rain. It didn’t run. Yesterday was forecasted for rain but it didn’t rain. No run. Rachio hasn’t run in 10 days.

Ryan Buckner

Have you looked at the Water Journal. It may help you understand why your system did or did not run. Go to Irrigation → Zones then select a zone and the Soil Moisture.

Also did you pick a specific weather station or let it aggregate from those around you. You can look up the actual weather stations and see if they have reported rain.

It’s possible your lawn doesn’t need watering yet. Likely even. Your settings may need to be tweaked in terms of soil and moisture depletion and so forth.

It’s also possible you’d be better choosing a specific weather station. There is one in my area that had a problem and wasn’t reporting any rain. So I switch to another and was much better off.

Update to the update. HK fail.

I have specific weather station based on recommendations on this community site.