Ice, Ice baby

Rain bird makes a wireless rain & freeze sensor all in one. It has adjustable temp set points and will stop your iro just as you’d like.

This happened to me, too. About a week ago the sprinklers came on when temperatures were about 27 degrees. I freaked out because it’s an automatic citation if water enforcement were to see the ice. This has never happened before. It would seem that Rachio would not run if a freeze is forecasted. Now i have my system on standby and water manually as needed.

That exact issue was one of the reasons I went with Rainmachine over Rachio (tested both side by side for 2 months).
The parsers are forced to fetch new weather data 6 minutes before the scheduled program run. And since I’m connected to 2 WUnderground stations a mere 1 mile from my house the data is a local as it can be short of having a station in my own backyard. I can also set the temp at which the freeze triggers.

Seems like a simple enough fix: rather than getting the current temp, Rachio could get the forecast low for the next few hours.

If low temperature within the next three hours is below 33F, then FreezeDelay.

Since they are a software company, a simple software fix seems like a rational approach. If you wanted to get dynamic (who who doesn’t love to get dynamic??) then you could assign a time window based on the watering interval. So if Rachio wants to water for a total of 55 minutes, then check if there’s a freeze temperature forecast within the next 55mins*2 or something.

Temperature forecast for the next few hours are plenty accurate for this use.

@Lngtrm1: I also live in DFW and have an Iro2 controller. I also water overnight. I connected the rain/freeze sensor from my old system (irritrol rfs-1000) to my Rachio system when I installed it. On 10/27 and 10/28, when the temperature dipped to near freezing, my rain/freeze sensor triggered Rachio to block watering. The Rachio app notified me that the sensor had been activated and it rescheduled the watering for the next day but since it was near freezing two nights in a row, it had to push out until 10/29 when it was warmer again. At that point, it caught itself up on the watering it had missed and everything went back to normal. It was automatic and seamless. I would highly recommend the Irritrol RFS-1000 as it triggers when air temps are in the mid to upper 30s, not just right at freezing. I believe this should solve your problem. Good luck!

Thanks, running that to ground now.

Have you installed or tested this product?

I note that the articles provided by rachio dont include wiring for freeze, just rain. Is it the same?

I hope this doesn’t get buried but…this issue is really frustrating.

Today at a user’s suggestion, I start looking into freeze sensors…I note that Rachio is nice enough to provide rain sensor info (all the while telling you you should be using “weather Intelligence” instead, but of course it inst available in “flex daily” but they fail to mention this…grrrr).

But no info on freeze sensor??? How does a Colorado company skip freeze sensors but include rain sensors in its support efforts?

Has the Cannabis testing been suspended? Is there a setting to tell me how close R&D is to a dispensary?


@lngtrm1 I have my Irritrol RFS-1000 wired into the Rachio controller as a rain sensor. When the RFS-1000 triggers under near-freezing conditions, the Rachio controller simply thinks it is raining and skips the watering. The app sends me a notification saying the “Rain Sensor Activated” when this happens. (See screen capture below.) Clearly, it doesn’t know the difference between a rain event and a freeze event, but I don’t think we care. Even though the scheduled watering gets delayed, because no precipitation is measured at the nearby weather stations my Rachio pulls data from, it doesn’t skew the soil moisture content calculations and the planned watering still occurs as soon as temperatures rise on a subsequent night.

Forgive me if I’m stating something you already know, but your grass is on the verge of going dormant if it hasn’t already. I plan to simply shut off the zones that water my grass in the next week or two and restart them once new growth starts to appear. The best way to avoid watering when it’s frozen is to simply not water. :slight_smile: (Again, forgive me if I’m stating the obvious.)


Thanks Paul, I’m trying to make the point that rain and freeze sensing are kind of blocking and tackling in football parlance. It just seems to be kind of overlooked in terms of support guidance. My guess is the promise of “Weather intelligence” or “flex daily” somehow convinced the company the external sensor(s) was/were unnecessary but it/they obviously is/are.

As for Texas dormancy I consider winter to be one of our driest periods and I have many shrubs, ground covers etc etc that need/expect a little water in the winter. Nothing worse than dry plants and harsh cold on the landscape. If you’re sprinkling pots even more so. It was 92 here yesterday!

So if this controller is smart it would water infrequently in the winter so I dont have to worry about too dry or when to rev it up in the spring. Just sayin. :slight_smile:

In my view it has to be smart enough to handle winter or dumb enough to require user intervention so at least give us the settings in flex daily.


@Lngtrm1 Yeah, I agree. If I didn’t already have the rain/freeze sensor, I’d probably be complaining about the same shortcoming.

Regarding my watering comment, it was only for grass. My grass seems to have already stopped growing. I watered yesterday (as you said, it was 92 after all), but am planning to stop watering my grass (but not shrubs) pretty soon. I also use a service called “” from Texas A&M. They send out weekly watering recommendations and they’re already saying 0" water for this week. They seem to lean more on the side of water conservation than Rachio does, so that’s why I haven’t cut the water off just yet. I’ll keep an eye on Rachio and see what it wants to do. This will be my 1st winter with it (got it Spring 2017), so Rachio’s winter watering is new territory for me.

So are you going to buy a rain/freeze sensor? My RFS-1000 has been quite good. My parents also have one that has run without problems, so there are two data points for you. Rachio installation is very easy and is done in about 1 minute.


Yes I have used this sensor. It triggers either on rain or freeze using one input to the controller. (Freeze is triggered just as rain). Rachio also has a very specific set of instructions on wiring. I have seen the freeze go off, however I would state I haven’t specifically used that function. I live in MN, so I generally try to have my system blown out before the first freeze. So for me it’s an added function I generally don’t need. I understand the frustration with the programming, but adding a sensor is the one true way to fix this without counting on some weatherstation likley some number of miles from your house.

Why can’t Rachio allow the user to change the freeze threshold for all types of schedules,not just fixed ones?Seems easy enough to program in.

Hi @edbianc,

This is a great point and a feature that we actually intend to address with our upcoming V3 Release. I encourage you to stay tuned for more information!

Again it can also be done with IFTTT. Even better is that a freeze sensor only blocks if it is freezing. You could water and then a couple of hours later the temperature goes below freezing and the standing water makes slippery ice and kills plants.With IFTTT you can set a freeze delay based on the forecast even before it freezes and you water. There is a whole list of others. You can see there is one for if it is really windy also.

Canbabis testing? Holy cow. The whole state must be on dope.

Most people install a rain freeze sensor combo. For freeze, when a temperature of 37 degrees is connected it breaks the connection to the common wire. Same for rain sensor. When rainfall hits the sensor it breaks the connection to the common. Freeze sensors are probably not mentioned by Rachio because irrigation winterization is a common practice in much of the country.

If the freeze sensor is connected such that it breaks the common wire connection to the solenoids, then while this will work, it allows the Iro2 to ‘think’ that it’s watering, causing moisture tracking to be badly messed up.

Instead, the freeze sensor can be connected to the Iro2’s SC and S1 terminals, along with enabling Sensor 1 for ‘rain.’ You’ll get the same (non) watering action, and, moisture tracking is correctly told that no water was put down.

This is what I’m doing now. Opening and closing the SC/S1 connection as a function of outside temperature. It’s working well.

BTW, my comments here are only for Flex Daily mode.

Best regards,


1 Like

When a freeze sensor halts watering, no valves will turn on. It’s like the controller is in standby mode. ET is used to calculate soil depletion so a freeze delay has no relationship to moisture in the soil… So in no way could I see a scenario how Rachio would think the controller is running. In areas of the country that have a real winter, no supplemental watering is needed unless there has been no precipitation. Only newly planted trees and shrubs need watering with a garden hose to avoid freeze damage. Dormant Bermudagrass needs about a half inch of moisture each winter month.

I believe if a freeze sensor is connected in a manner of interrupting the common wire to the solenoids the Iro2 has no way to know about this, and thus moisture integration calculations are adversely affected.

I believe you must connect the freeze sensor to the SC and the S1 or 2 terminals, and tell the Iro2 it’s present via configuration, in order for moisture calculations to be kept intact.

This is for Flex Daily mode.

Best regards,


1 Like