Major weather bug makes Rachio Useless

I have 4 rachio 3’s installed. Real issue with weather and evaporation calculations. Yesterdays weather showed that it was 84 degrees - which it was - , but when today came along, it shows yesterday was 64 degrees. Historical temperatures are laa 20 or so degrees below actual. Now that’s a nuisance, but the real problem is that it calculated yesterdays evaporation loss based on 64 degree heat, not 84, so it’s continually underestimating water loss and everything is dying. When I looked at it yesterday, the soil moisture display showed that it was going to reduce the Evap by .14, but it reduced it by only .09. This happens every day on every zone.
What the hell is going on? If this isn’t fixed, I’m going to rip it all out and go with something else!
I’m using data from aggregate weather stations.

And just to put things in perspective, I get ET data from CIMIS daily. CIMIS moisture reduction - .27. Rachio - .09.

Hey @comet48! I’m so sorry for the incredibly frustrating experience. I’m not totally sure what’s happening here but am going to make sure a team member takes a look!

@comet48 I’m having the engineering team review and will let you know what they find out!


@comet48 For observations the weather service being used for your lat/long is KNUQ (we use the closest national station to derive ET).

It does look like it is reporting in the mid 60’s for maximum temperature observations.

For that part of town, is that data incorrect? Is that station reporting incorrectly?


I can speak to the KNUQ observations, since I live near there also. KNUQ is an airport location on the shore of San Francisco Bay, where it receives cooling breezes during much of the summer. The climate there is not representative of nearby locations that are farther inland, which can easily be warmer by 20 degrees or more. Additionally, it is quite common to have a marine layer temperature inversion, so higher elevations can be much warmer than sea level locations.

This leads to the frustration I have had with choosing a suitable weather station. The airports are all near the bay, so they really aren’t representative of my home’s climate. There are NWS RAWS stations, which are pretty trustworthy when they work, but they are unattended remote stations that sometimes go down for long periods. There are plenty of PWSs in my vicinity, which give representative observations when they work, but they sometimes go down or give wacko reports.

It seems to me that a good solution to this problem would be to select a number of local stations to use, collect observations from all of them, discard outliers, and aggregate the remaining data. This seems more trustworthy than depending on any single station, while still allowing use of local stations rather than NWS stations whose climate is different from mine.


Selected a local station - kcalosal227- made no difference. When 7/9 was “Today”, it showed that the temperature was to be 90 deg F, but now it shows that the temperature history for 7/9 is 64 degrees. A 26 degree differential. The Forecast ET for 7/9, zone 7 was 0.17. Its end of day calculation was 0.11, a 35% reduction. Its saying add an inch of water every 9 days to a lawn in full sun in 90 degree temperature. That’s a lawn killer. KCALOSAL227 showed a high of 87.8 deg F, average 69.4. Rachio shows it was high 64, low 57. Where did that come from?
Is Rachio using the same weather station for its “in day” forecast as it is using for its end of day ET calculation? My betting is that it is not, and that it doesn’t have the code to translate the kcalosalxx weather stations.
I’ve got approximately $800 invested in these 4 Rachios. Too late to return them now. Warranty isn’t going to fix this bug. What’s my recourse? Willing to return to Rachio with receipts. Can’t keep using them. My lawns are dying!
One thing a weather station has to do is accurately calculate ET. Rachio does not.

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I hear you on this limitation. Here in rural Northern California Rachio uses the nearest local NOAA station - 25 miles away on the other side of the valley. The climate is a bit different! So in the summer I end up having to select a specific NOAA station that is in the right climate, and it is 31 miles away. We don’t get rain in the summer so it’s fine that Rachio isn’t using my PWS (rain is all Rachio uses from a PWS).

On your weather intelligence map, which is limited in distance from you, can you find and select a NWS/NOAA station located in an area with a similar inland climate? I suppose if you can’t, may try setting a different address from the Rachio somewhere that is near a seemingly good NWS/NOAA station that reflects your climate.

I’m not sure how Rachio can solve the problem of a lack of NWS stations with very accurate measurements in areas with sharp changes in climate (e.g. from coastal Bay Area to inland - as you’ve shown the temperature differences over a few miles can be HUGE).

I actually like this short term workaround @Kubisuro!

Good news! We are actively looking at using interpolated weather for observations that will remove this problem altogether. In the analysis phase now to make sure the data looks appropriate, but this could alleviate these proximity and micro-climate issues that some of our customers experience.



Good news on the interpolated weather.

@franz Franz- My rainbird rain sensor works great at providing my Rachio 3 actual, yard-specific rain and drying timing. Can you incorporate the signal transition timing that the Rachio 3 already receives from connected rain sensors (i.e. 1. Exact time of rain sensor OFF to ON signal transition, 2. Duration of ON signal, and 3. Exact time of ON to OFF signal transition) into the interpolation? As a 4th data point… if my Rachio 3 allowed me to enter the Rainbird sensor’s setpoint as a sensor setting in the Rachio settings, Rachio would have even better micro-climate granularity of recent and realtime weather insight to share with all of my neighbors!

Good news on planned upgrade. No close NWS sites, but tons of PWS sites. I’m in the Bay Area, the land of micro climates.
I’d be happy to install a local weather station if I had to, but it would have to provide data to each of my four Rachio 3’s.
Love to be a beta site for the interpolated weather. You should use the PWS station data. There are a vast number of good working sites around here.

While I have you on the line. Two other requests, given that I have 4 x Rachios.

  1. Cloud based scheduling, so that the units don’t water at the same time. Hard to coordinate when you have lots of units
  2. Access to a single flow meter by multiple Rachios. Gets expensive when you have multiple units.

Your KNUQ data looks bad. 7/9 no data from 06:55 until 23:15, hence the very low max temperatures and ET’s. Same for 7/8. The input data is crap :slight_smile: Checked from the web page. Same issue!

I just received a notification from Rachio that there is a closer weather station, kcalosal227. It’s a PWS station, and as stated by franz above, these are only used to determine rainfall. So if I select kaclosal227 as recommended by Rachio, the controller will revert back to using KNUQ, the closest NWS/NOAA station, to calculate ET. And as I have already mentioned, KNUQ fails to provide any weather data after 6:55 am on any day. Rachio does not block, or allow me to be block, KNUQ.
Rachio advertises that it has access to over 300,000 weather stations, but it fails to mention that it uses almost none of them to determine ET loss.
So currently I’m forced to select KSJC (san jose airport) as my weather station to determine water loss and also use it for determining rainfall. Rainfall data from 11 miles away is pretty useless.
IMO Rachio needs to support the PWS weather stations for both rainfall and ET calculations, and also needs to block stations that fail to provide data, like KNUQ.

One has to wonder how many Rachio units in the bay area are linked to PWS stations, or selected the aggregating data option, and are getting crappy data from KNUQ. How many Rachio users understand that selecting a non NWS station lets Rachio select one for you, whether working or not, and uses that for ET calculations rather than the station you selected.

Are you able to set ET manually via advanced settings? I don’t know as I run a Rachio Gen 2 (have been for years). The CIMIS data is great when it works, but in my area—central valley—it’s not too good as many of the stations are inactive since 1 Jan 2020. So here’s how I work around it, ymmv obviously. I go into advanced settings for each zone and monthly set the ET based on my turf type and other data in conjunction with the UCD published data.

It’s not ideal. It takes more manual attention than I would prefer, but it does work. Does it use exactly the right amount of water? I doubt it. But using it my turf looks great 12-mo/yr with temps ranging from 110°F in the summer to 20°F in the winter and I am using < 50% of the water I used before installing it.

Like I said, not ideal, not perfect granularity, may not even be available on your Gen 3, and ymmv.


A little late to this party, but if you use a set of relays you could get 1 meter to 4 controllers. You would need to use solid state. For 4 meters, I’d probably use 2 SPDT relays. You probably would need to use a little transformer and resistor to power the relays and meter. I’d guess $70 in materials to put in a little box.