Rain Sensor and Internet Weather

Hi there - I have a suggestion for the combination of a rain sensor and Internet weather.

Currently if the Internet says it’s going to be sunny, but it rains at my house, my rain sensor will catch the mistake and shut off the water.

I would like to see the reverse implemented - If the Internet says it’s going to rain but my rain sensor never gets wet, then I’d like to see the controller detect that and then water the yard instead of waiting until the next cycle.

Also - A setting on the rain sensor config page where you could select what you have your sensor set to (1/8, 1/4, 1/2, 3/4, etc…) so the software could estimate how much rainfall you actually got at your house so that it could decide how much time to delay until the next watering would be cool. Example: You tell it that your sensor is set to 1/2 inch, and it decides that since your sensor is activated that means you actually got around 1/2 inch of rain, so it will delay the next watering for x days. If you had it set to 1/4 inch maybe it only delays for y days, etc…

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Absolutely. My Mini-Clik is set to 1/2". I’d love to configure that in the controller and over time let it learn based on weather how long the sensor takes to dry out. Then overlay that data to the evaporation rate to try and get a better idea of what my property’s micro-climate may have received compared to the closest NOAA station 3 miles away.

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I really like this idea, I think we are missing an opportunity by not gathering more data from rain sensors. They could have the potential to work as almost mini weather stations if we start gathering more data about thresholds and the amount of time it takes them to dry out.


Now you’re cooking with Coffee!

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Also, for those of us that have rain sensors, you could compare the weather data to rain sensor trigger points. If the sensor did not trigger, you know that enough rain was not received. If it did trigger, you know at least that many inches of rainfall was received. In other words, you could also get sophisticated and have users input their rain sensor’s precipitation settings into Rachio. If the amount of rain in the forecast is equal to or exceeds the amount collected by the sensor, you now have a known (or near known)precipitation level recieved in that location. You also have a precipitation rate. These values could supersede or supplement the forecasted amounts.

Again, user selectable feature…


Sounds very complicated…for not much more money you could get a cheap wireless weather station which would give you precise rainfall, temp, humidity etc local to your property so no clever interpolation, learning etc required from Rachio!

The Rachio would have to know the hourly chance of rain to do this, no?

I don’t want my skipped 4 AM schedule running at 8 PM (because my rain sensor has been dry) when the forecasted rain is still on track to arrive at 10:00 PM.

It’s really not that complicated at all. The Rainbird WR2 Rain Sensor already has set points that trigger the system not to water. So, if say, I set my sensor to shut off the system if I receive 1/2" of Rain, Rachio could use that data as a 100% confirmation that I got that much Rain. All we’d need is a location to plug our setting at. Simple promising and basic math can determine several things from that including:

  1. Precipitation rate/ hour
  2. Pricipitation level
  3. Precipitation levels in the region(using multiple sensors in the area)
    So, if the forecast says 1/2" of rain, and my sensor did not go off, Rachio knows that a less than forecasted event occurred. If it achieved the 1/2 inch but the forecast said it would be 1", using the rate per hour in combination with other sensors in the area, Rachio would be able build a reasonable predictive model that we probably got that 1" based on how fast we achieved that 1/2". It’s basically using what’s already there vs having customers going out and buying/maintaining a PWS.

My Mini-Clik is the same and currently set to 1/2". The challenge probably becomes if you receive 1/2" of rain, then 1/8" evaporates, then it rains again and you end up at 3/4" cumulative in the sensor. I’ve not observed my Mini-Clik enough to know when it deactivates if that means it is simply back under under 1/2" or the 1/2" it received has evaporated entirely.

It’s the former - As soon as they get under the setting they close the circuit again.

For example:
If you have the sensor set to 1/2", when the cork disks have absorbed enough water to expand 1/2", they will press down on the micro switch and open the circuit. The circuit will now stay open as long as the cork disks have enough moisture in them to stay expanded (If it keeps raining or even if it stops raining, then they slowly start to dry out)

Once they start to dry out, as soon as they contract below 1/2" (For arguments sake say 7/16" - Not sure if they are accurate to 1/16" or not) the switch will no longer be depressed and the circuit will close again allowing current to flow through and allowing the controller to water again.

TL:DR: It does not wait until it is all the way back to 0" to close the circuit.

It’s certainly an interesting theoretical challenge but I suspect trying to create some sophisticated decisions out of a simple on/off data point from the Mini-clik amounts to trying to make a silk purse out of a sow’s ear…I’m just not convinced it’s a commercial runner. Like I said…just buy a weather station…it’s not “difficult to maintain” and if it was all about using “what was already there” IMHO you wouldn’t have paid for a new Rachio!

The Rain Bird WR2 receives weather data every 45 seconds and has three modes of operation to handle Rainfall:

  1. Accumulation - Collects water up to 6 preset levels ranging from 1/8th" up to 1/2"
  2. Quick Shutoff - Suspends irrigation immediately whenever Rain is detected(no accumulation required)
  3. Manual delay/bypass - Delays watering 72hours after an event or bypass Rain sensor altogether.

Rachio can use item one with user input set points to determine both if a Rain event occurred and at least the set point amount of rainfall occurred. They could compare data to the forecast and know that the forecasted event occurred and adjust the schedule accordingly. If the set point amount of Rain was never achieved (Rain sensor not triggered) then Rachio would not adjust the scheduled irrigation. This would be a semi-quantitative test.

Rachio using item two would be just confirmation that the forecasted Rain event occurred. They could use this solely as a qualitative test.

With various users in the area having mixed combinations of 1 and 2, Rachio could gather a significant amount of predictive data and use it to adjust schedules.

Now, in item one, to handle the Clik sensor limitations of the unit filling up, some water evaporating, and other accuracy issues associated with similar issues, Rachio would have to incorporate a simple tank evaporation rate model using temp and humidity and air flow data. This would be simpler than the sophisticated evapotrans scheme used for vegetation and can be found here:


With the rate of evaporation calculation and use of point one as a semi-quantitative method, Rachio could track the amount of accumulation over time. For instance, received 1/2" on Tuesday and sensor was triggered. That 1/2"=X. Wednesday, experienced high temperatures and humidity which cause the sensor to dry below the set point, sensor triggers again that rain delay is suspended. The Delta X = X - (Calculated evaporation taken place up to that point of sensor trigger). Now, if another Rain event occurs late Wednesday, we look for when the sensor triggers and calculate the difference between Delta X - any additional evaporation that should have occurred between the last two sensor events, add to that the additionally calculated rain fall (we know the estimated rate because we use the times between sensor triggers), we now have another rainfall accumulation amount. We can then use this data along with our predictive model to determine when the sensor should dry out. If it takes longer to dry out and it wasn’t due to temperature humidity, it had to be due to additional rainfall. We can compare this to our forecast and do other nifty things. If coupled with data from many sensors in the region you now have a very powerful verification and schedule adjustment tool.

Finally, you can use this data to determine irrigation savings. Rainbird claims up to 35% savings through use of the WR2 alone. We have to be seeing greater than this amount of savings. Rachio is just not using the data. The way to use the sensor trigger data to determine water savings with any of the schedules is to setup a separate placeholder table to capture every Rain sensor event period. An event period is defined as the time between initial trigger of the sensor up to to that of the sensor off state being triggered. Then, allow the existing Rachio schedule to work based on the forecast just as it does now. However, whenever a sensor is triggered, they must then compare the forecasted schedule to the duration of the sensor event period. If the Rachio would have watered based on the forecast, but didn’t due Rain sensor event period, that precipitation amount saved due to rain fall should go into the bank as a water savings. The comparison should occur for the duration of the event period and savings applied accordingly. Further, all of the accumulation data from scenarios one or two above should be used in comparison to the forecast to reduce or increase the amount of irrigation that Rachio provides.

Hope this all makes sense…

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The OP’s request was for the Rachio to be able to look at the rain sensor and make the decision to run any schedule that it skipped earlier in the day because it thought rain was coming.

So on that note, I’m still confused. I have a daily Flex schedule set to go off at 4:00 AM. If the forecast for the day shows “one-half inch of rain expected”, Rachio will skip the schedule for the day.

Rachio can look at my rain sensor any time during that day to tell if rain actually fell. But unless it also knows if rain is forecasted for the remainder of that day (or not), I don’t see how it can make a decision on whether to run the schedule that it skipped earlier in the day.

So that’s my question, back to the OP’s request. Does the Rachio receive an hourly precipitation forecast? Because if it doesn’t, I don’t see how it could ever make a proper decision in that regard.

If you use flex schedules, I would say the answer is no.

Without further programming (such what I suggested above)) it is not possible since Rachio relies on the forecast and soil moisture levels with Flex. The only way I can see it irrigating is if the the forecasted rain amount is low and a run is scheduled to make up the difference in your moisture balance.

With Flex, “The calendar view (watering schedule) uses forecast data to estimate the next scheduled watering. However, if the observed weather is hotter/cooler and/or more precipitation/less precipitation is reported than forecasted, the Flexible Daily schedule may change. Every night at midnight the schedule will update the forecasted weather data with observed weather data and applies a checkbook style accounting of the moisture level for each zone. Any time a zone is calculated to reach its allowed depletion, the zone will be watered.”

The feature that checks the forecast hourly is called Rain Skip (http://support.rachio.com/article/511-rain-skip). My understanding is that Rain Skip doesn’t work with Flex schedules. Here is a note from McKenzie on it from another thread where I was asking about water savings and Rain sensors.

mckynzeeCommunity Moderator1d
Jumping it to further clarify-

We determine “Water Saved” by adding up any runs that are skipped due to Weather Intelligence features (ie Rain Skip, Freeze Skip, Climate Skip). Since flex scheduling doesn’t necessarily skip (I would call it more of a push), this feature is not available on Flex schedules.

I think ultimately the best comparison is comparing “pre-Rachio” water usage to “post-Rachio”. I love seeing YOY water bills for this exact reason. However, it would be difficult to capture your pre Rachio watering habits. Any thoughts/ideas?