Personal Weather Station - what to buy?

@Skywatch, thank you for sharing your findings with us. We hope by allowing users the ability to select their preferred weather station, that they will all take some time review the weather reports from their nearby stations and make the best selection possible.

Same can be said of price and installation time. I also believe placement of the weather station could be argued as more important than the station itself.

Do you have any tips on how to install and/or configure a Davis station?

Best, Emil

I am using a davis vantage pro2 and recently purchased the weaterlink ip ($230). I am using a powerline ethernet adapter Setup is “simple” if you follow the directions found on the web. Wunderground simple required inputting your username and password. NOAA required requesting a station id, setting up lat/lon/elevation, emailing noaa to let them know you are broadcasting and waiting (in my case 1 week) for the station to to be listed. It was then selectable on IRO.

@dentalpain, have you had any issues with the quality of data being reported? Or delays in reporting?

Just to confirm, is this the WeatherLinkIP you’re using?

Could you shed anymore light on this setup? I’d like to add an article about this to our knowledge base :smile:

Best, Emil

I have had no issues with quality or timeliness. I dont know how quickly IRO updates PWS data but most sites seems to be no more than 15 belated. Yes I am using weatherlinkIP, you linked to the correct product. It connected via an interface port on the back of my Davis and I used powerline over ethernet on the other. You then create an account and log into Davis’ weatherlink website. There you add accounts, like wunderground and CWOP. Each setup is unique but directions can be found online.

Even though people tend to say the installation is difficult, it’s really not. The Davis station installation isn’t much different than any other make. I’ve had LaCrosse and Oregon Scientific.

The Davis installs in 2 ways, either attaching to a pole via U bolt or screws to a wooden post. The mounting hardware is included.

The only real difference is the VP2 sensor unit is heavier. No biggie.

Awesome, thanks @dentalpain and @Skywatch, we appreciate your feedback. Hopefully this will encourage others to consider setting up a PWS for their Iro.

Just curious, not sure if you monitor other stations in your area, but if you had to ballpark how much more accurate your Iro was due to having a PWS on site versus using another PWS or NWS, what do you think the the percentage would be?

I don’t yet own an Iro but in September I’m hopefully going to buy. I found out about Rachio Iro from a neighbor who’s Iro is connected to my station and contacted me commending my data and equipment. Currently we have a 1998 Rainbird controller that doesn’t work anymore.

@emil I can say that my PWS is about 2 miles from a small airport’s weather station. My temps are usually +/- up to ~8 degrees which makes sense due to the microclimates we get on the coast. The fog can get trapped in places and have a noticeable affect on temperature. For rainfall, I’ll have to wait until it actually rains here in CA :slight_smile: Since temperature affects evap rates I’d say it’s definitely useful. The real impact will be when we get rain which can vary quite a bit even a mile away.

There is another reliable PWS about half a mile from me, his readings are in line with mine so I could have used his but that’s no fun.

I know that the storms we typically get are very spotty, as we can get a half inch of rain at the house and nothing a mile away. Considering there are no PWS less than 5 miles from me, I decided to get the Netatmo (with rain gauge) and set it up last weekend. It rained over the last couple days and I compared my data to other weather stations in the area and it varied quite a bit.

Just to be sure though I used a catch cup to compare the inches of rain to the Netatmo and if my calculations are correct, I believe the initial calibration is a little off.

This is what I came up with:

Heavy rain:
Catch cup - (140ml / 16in2) x .06 = .525 in - Compared to the rain gauge reading, which was .453

Light rain:
Catch cup - (15ml / 16in2) x .06 = .056 in - Compared to the rain gauge reading, which was .040

@emil, do those calculations (based on one of your previous posts) look correct?

From what I have read though, it sounds like the Netatmo is pretty easy to calibrate, which I will try to do this weekend.

I live in Florida, where it can rain on one side of the street and not the other. Needless to say a PWS 7 miles away was inaccurate 75% of the time it rained, and 100% of the time on accumulated precipitation. Now, its bang on and I saved $XX on a wired rain “sensor”. Having accurate data show in my moisture logs was worth the expense (I plan on a 15 year + life span on the Davis). If anyone needs any help, message me or post here, I am happy to help.

I don’t think these negate the rain sensor. We got rain here at 4 am this morning, well after rachio scheduled my zones to run, but my sensor has tripped and rachio now has opportunity to observe this precip and adjust accordingly.

cfwiggum said: “I know that the storms we typically get are very spotty, as we can get a half inch of rain at the house and nothing a mile away.”

This is exceptionally true for those of us in the suburbs of the Dallas - Ft. Worth Metroplex. I’m better off taking my chances with a PWS that’s 0.5 mi away, versus lining up with DFW airport. While it may seem odd at first, in fact there is little alignment of rainfall at the airport versus my location (or for that matter, many other locations).

Best regards,


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The way I understand it a rain guage would only stop actual irrigation from 1 hour prior and during the time it is irrigating (50 mins for me). So a 1 hour 50 min window starting at 4 am (not too many rain events starting at 4 am here). I bet that when the IRO went to check for weather 1 hour prior to running it would see the rain happening or forecast and stop watering anyways. I still don’t see the point of a standalone rain sensor, maybe someone at Rachio can shed some light on this. Does a PWS take the place of a rain guage, what is one missing if they only have a PWS?

I love the fact my IRO knows that I got .48" yesterday (over it rained more than your predefined cut off .25 for example).

Not entirely true, the sensor will prevent irrigation as long as it is wet, so mine is set for 1/8 and usually takes an entire day to dry out at that precip rate. but keep it in the back of your if you have the problem I described above or suffer from some of rachio’is unfortunate outages in weather data. For me my micro climate does not meet forecasts just often enough to justify the unit for this reason alone (and I’ll get a pws to increase its accuracy this winter). It is just a cheap fail safe you can add to the system, but my manicupality charges too much for water as it is (usage tiers) so that is another driving motivator. But yes, I have seen rachio be at least 4 hours behind for my area on several occasions.

Yes, a rain sensor does not negate this data, I like having this data as well. My main point is that they are not mutually exclusive and cheap enough to justify the failure that rachio has had as well as there weather data vendor to further the units efficiency.

IMHO I still like the concept of a physical rain sensor. The data does not lie, and is not affected by a lapse or gap in reporting precipitation data. I view it as a type of cheap insurance.

A PWS is very helpful for flex schedules in having the most accurate weather data, along with fixed schedules for having the most accurate recorded precipitation data.


@Skywatch, hope to see you become a user next month :smile:. Please let us know if you have any questions we can help answer.

@cfwiggum, good point! Thank you for confirming.

@jimB34m, sorry for the delay in getting back to you. Any luck on calibrating your Iro?

@dentalpain, please keep us posted on your water savings! We love hearing his feedback from our users.

@plainsane, totally agree! It’s a very cheap insurance plan for anytime the forecasts are wrong.

@dentalpain, great questions. Rain forecasts are tricky to understand. According to the U.S. National Weather Service (NWS), POP is the probability of exceeding more than 0.01 inches (0.25 mm) of precipitation. Additionally, while the forecast might call for 1/2 inch of rain, if there is a 100% probability of rain covering one half of a city, and a 0% probability of rain on the other half of the city, the POP for the city would be 50%. A 50% chance of a rainstorm covering the entire city would also lead to a POP of 50%. The POP can be expressed as a combination of degree of confidence AND area coverage. As you can see, the variables start to add up and there’s a limit of analysis paralysis :wink:

A rain sensor does not replace a PWS. It simply will interrupt the common wire anytime it senses moisture and disable the controller from functioning. Think of it as an insurance policy for bad weather forecasts.

@plainsane, good to know. We’ll reach out to our weather service provider to see if there’s anything that can be done to speed up the data transfer.

Thank you everyone for your feedback and support. Please keep this conversation going if you think of anything new to add!

Best, Emil

it is transient and uncommon, I’m assuming it is the weather station I’m using is lagging. More often than not it is micro climate that runs it in the rain or shortly after rain. But it has happened 1 time for certain.

I’m installing a pws at the end of the winter break, I was really just trying to illustrate that fact that there can be things outside of rachio’s control that would necessitate a sensor to avoid running it in the rain.

Yes, thanks Emil. Seems that the rain gauge, for the Netatmo, was low by about 25%. Haven’t gotten a chance to do another catch cup comparison test though.

@jimB34m did you calibrate your Netatmo rain gauge or just connect it and use the default settings? I calibrated mine and it seems to be reasonably accurate. Calibration settings are found on website under settings (gear icon) -> calibration.

I connected it and used it for a few weeks without knowing if the calibration was off or not. I then read a bit on Netatmo’s forums about how they tend to be way off, out of the box. When rain was predicted, I set up a catch cup and compared my own calculation to my rain gauge and confirmed it was off. I then did the steps you posted above to calibrate it. Just waiting to do another catch cup test and compare it, so I can see how I did in the calibration.