I think something like this would be more sensitive:
Is it reliable masterkenobi? 
I like the 433MHz stuff since it doesnt use much battery.
at first it was quite reliable. it did send an alert before the rain gets too heavy. but after awhile, it has stopped working. maybe the PCB got damaged by the elements or no more battery. anyway, i don’t have the time to climb up the roof to check. i still got 10 to 20 sensors waiting for me to change the battery.
I wonder what people in Germany are using to reliably detect rain. I am using dark sky right now, but it is not as accurate as for e.g. the USA. I was experimenting with dark_sky_precip, but it seems to show rain quite often. Therefore, one has to also look at the probability (dark_sky_precip_probability) to figure out if rain is likely or not. I would be interested in your thresholds you are using for your notifications or even other ways to detect rain.
Did you find out a good solution to detect rain?
I’m using this now. Still working until now.
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I look out the window… 
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You beat me to it by 4 minutes
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Well, if you want to do something real based on whether it rains or not, that is not much helpful specially when you travel often…
If anyone goes with the xiaomi door sensor style, I’ve created a case for it: Rainsensor with Xiaomi Door Sensor by ThaNerd - Thingiverse
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I use this sensor:
High sensitivity thin film capacitive rain sensor.
It’s tiny, entirely insulated (so no exposed metal and it doesn’t degrade due to the elements) and very sensitive. It also has an integrated NTC and heating element for de-icing, but it also works without them.
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I have a hard time finding these anywhere, at least in the UK. Quick question: How does a capacitive sensor different from the usual, cheap and more exposed ones ?
I ordered mine directly from RadioControlli in Italy (I got a few of their RF modules too, they have some really nice good quality stuff).
The physical principle is different. The ‘normal’ ones measure resistance. When rain falls onto the exposed PCB traces, it connects the traces and lowers the overall resistance as rain water conducts electricity. The more rain, the lower the resistance. For that to work, the electrical traces have to be exposed so that the water can touch and ‘short’ them. That will make them degrade easily with dirt and corrosion.
Capacitive sensors work differently. They don’t measure the resistance but the capacitance. The traces are completely insulated in a non conductive resin substrate, forming a capacitor. No water ever gets to them, so they will not degrade. When rain drops fall onto the (insulated) surface, the value of the capacitor changes, because the water acts as a dielectric. This works without direct electric contact. It’s similar to the way touch screens operate. The detection circuit measures the capacitance of the rain sensor. The more rain drops, the higher the capacitance.
Even though they look similar, both aren’t directly interchangeable. They need their own detection circuits, due to the different physical properties measured in each (resistance vs capacitance).
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I might have to get them from italy. I see some on eBay but all from China. I did order a tipping bucket rain sensor from Aliexpress to also measure rainfall.
Thanks, very useful info.
Even though they look similar, both aren’t directly interchangeable. They need their own detection circuits, due to the different physical properties measured in each (resistance vs capacitance).
Would they work with a 433 door sensor or a aqara zigbee sensor ? Or do i need a somewhat more digital processing here? The ones i originally ordered
https://www.amazon.co.uk/gp/product/B07V5QWXNS/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&th=1
also come with a little sensor, which actually allows for snow/humidity but i expect that needs some more work from me to process the signal software wise. I have to check the pdf that came with it though.
Not without additional electronics.
Rain, snow, humidity, it’s all the same to the sensor. It will detect anything that lowers the resistance and/or shorts the tracks on the pcb and you can’t distinguish between them. If you take anything conductive, like a metal screw or nail, aluminium foil or anything like that and put it onto the sensor, it will also detect it as ‘rain’. This is all very very basic stuff.
I guess you can just use the ones you already have and see how it goes.
I found this useful link : Resistive Rain Sensor Products
I use a VELUX rain sensor since many years now and it is very reliable.
I will try the Kemo that seems profesionnal as well.
I tried chinese PCB plates a long time ago and it works 2/3 months before to die. Corrosion, UV, etc … are probably the cause of their death 
!
Can I ask how you got this as a sensor in Home Assistant?
Solid state rain sensors look like a nice approach as well 
Just installed Hydreon RG 15. I have Velux rain sensor and a Hunter Rainclick. Neither can I integrate; so time for a full on rain sensor!
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That’s an interesting concept. Please post back here when you’ve got some experience.
I’d especially like to know how accurate it is when conditions get beyond just counting drops. For example, you can have a torrential rain where inches of water per hour are coming down, or a steady rain with much less volume. It seems to me that in both cases, the sensor would just stay wet all over. How would it know the volume of water running down the outside of the case?
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