I am looking for a solution that have instant rain detection.
Hi Michael,
Iām using a modified Aqara Leak sensor for this as I have already got other Aqara zigbee sensors
https://www.aqara.com/eu/water_leak_sensor.html
attached to the screwable contacts of the sensor is a rain sensor pad like this one
Compared to more expensive rain sensors, which also have a heated sensor pad to allow for quicker drying, my solution takes a bit longer to register when the rain stops, but rain detection is instant, which was the important point for me.
Hope this helps.
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Some more information would be niceā¦ What are you willing to spend? Use case? How instant does it have to be? Do you have any existing hardware you could useā¦?
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I use that one, too. Itās actually a binary input you can attach to any sensor that has a potential free IN.
Which protocols do you have in your home already?
The Velbus weather station has rain detection, with a MM value (rather than a Boolean state)
I really am very happy about the instant boolean state of my setup.
Just today again I had my home shout at me several times āItās staring to rain , some windows are openā 
even when there was only a very slight drizzle, with a mm value weather station very close to me not registering any significant (i.e. none at all) mm values for all of the occurrences.
So, I think, for instant rain warnings a boolean solution is definitely preferable. For longer term rain quantity logging I very much enjoy the mm history.
Since the Aqara Leak sensor does have the logic already with its two existing sensor contacts, I have the moisture detection plate directly attached to it. The included logic module being unused in my case, but definitely helpful with other sensors.
Without the module itās an analog value, so if you connect that to an analog IN, you can even change the threshold when to trigger.
Or use the board, it has a potentiometer so you can at least adjust thresholds manually.
I agree rain āhistoryā is irrelevant (unless meteorology is your hobby), that you can get from an internet service as well. But a tuneable threshold is. Also think of non-rain weather conditions you might want this to trigger on such as fog to come up.
Exactly, and the job the Aqara Leak sensor does with the pad without any potentiometer option/burden is really impressive. Slightest bit of drizzle and it kicks in. Thatās why I mentioned this combo when I saw the āInstantā in the headline. Michael might have been very brief, but it sure was to the point of what he seems to be looking for 
++ Instant slightest drizzle trigger
++ 1.5-2 year battery life with small CR2032
- the pad doesn't get heated for instant rain stop trigger
-- sometimes during early hour of night false positive; dew => rain trigger, same reason as above
Aqara stuff needs a ZigBee coordinator or gateway, doesnāt it on OH side ?
I just watched your video from marts regarding setting up wind/light alarm for āUncle Samā to be used to control his blinds from windspeed and sunlight. I really like the way this weatherstation operates in the Velbus enviroment.
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Yes, Aqara stuff are all zigbee, so need a gateway ot zigbee coordinator.
I use a āHomeMatic Funk-Regensensorā. It is rock-solid, instant and has a heating that I switch via rule to have a faster āno rain anymoreā detection.
You can change the detection level (the sensor is more or less a resistance).
It is homematic though, so you need a homematic central unit.
And itās 50ā¦100ā¬.
My other rain sensor, a āPOPP POPE700168 Z-Rain Regensensorā is not instant, but takes up to 4 min and does not detect slow rain due to the seesaw mechanism. It is only suited to measure amount of rain per day/week or so.
Netatmo with Rain Sensor
Hydreon RG11 optical rain sensorā¦ It has an instant rain detection mode which provides quick response. Great device, but you need to order directly in the US.
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I use this Tempest Weather Station
It has all the usual weather sensors (wind speed/direction, temperature, humidity, pressure etc), a haptic sensor (that senses individual rain drops - and works very well) that gives instant notification of rain events, plus rain rate and quantity.
Itās solar powered, and works in extreme temperatures (-40 to 45 deg C). It uses sub GHz radio to transmit data to itās WiFi hub (range up to 1km).
Best of all it has an open API, with several different methods of accessing. I use the UDP data broadcast on my local network for real time data feeding into OpenHab.
This gives me instant notification as soon as it starts to rain, you can also get lightning notifications as it has a lightning sensor also.
Itās a fantastic device for the price.
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If you are looking for a KNX based solution, there are several alternatives. I use a MDT SCN-RS1R.01. This one is configurable regarding the sensitivity of the rain detection and it works quite well for me. The system has an automatic heating system for the detection plate to enhance detection acuracy.
I donāt think anybody reasonably would do that with openHAB offering so many RF alternatives.
KNX is $$$ and even more so because you must put a wire through the wall and to a suitable location.
Sorry for my short description.
I have now zwave and rx433.
I already have popp rain sensor and that is to slow.
RG11 does not detect snow. Tempest does not deliver to Sweden.
I am know looking at https://shop.bb-sensors.com/en/Humidity-measurement/Humidity-switching-devices-controllers/Rain-detector-unit-in-housing-24-V.html
I took the 12V version of that one and put a Fibaro FGBS-222 into the box to to make it speak z-wave. Works.
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