Someone using reliable OUTDOOR Humidity Sensors?

Ahahaha … you can continue to post, all that is shared is an asset for others imho.

I have been using Sensiron T/RH sensors for more than a decade in outdoor environments and they are great, highly reliable and highly repeatable sensors. I do not use epoxy to protect them because of the high thermal mass of the epoxy which would impact the fast response times of these sensors required for my application. Instead I use an amazingly thin and amazingly viscous military grade conformal coating covering the PCB and connectors exposing only the small area of the sensing element which is protected by the optional sensor filter cover.


And this coat is? Do you have a name of it?

Warning - it is amazing viscous stuff. The first few times I used this material I got some on PCB molex connector pins and it insulated them!! I had to scrape it off with a knife

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Found something interesting:

Ready-made device with an SHT20 inside. Guess I gonna give it a try!

Be sure to read Dragino LHT65 and network coverage when trying to make a LHT65 join with TTN. (Or add some notes to your order that you need a proper AppEUI.)

Oh wow, pretty scary :flushed:
Many thanks for having pointed that out @arjanvanb !!!


@suendermarkus you ask for an outdoorLoRaNode.
Hopefully i can help you. :wink:

In our COM, we develop an LoRaNode caled Nucleon-Weathernode (WetterNode).

It is an Node based on a Arduino pro Mini, Hope RF 95, @Wijnand `s PCB and an BME280 as Sensor.

The sparepartlist you can find here:

For Weather housing i use old Plastic bottles 0,5 l .(up cycling :wink:)

A Node like this hangs around 1 year on north side at my apartment 1st floor.
Another at the east side.

Here in Germany near Denmark we have mostly harsh weather with many rainy days.
BUT the Nodes will work and do their work!

The Software part you can find here:

A sneak peak for results are in our Grafana. This Node are build at a learning session about LoRa and LoRaWAN made by @DasNordlicht at November 2018.

Have a look:

The second one on east side:

Feel free to ask something!



PS: There is an description on our Website (German). :


… forgot

A description for the WeatherNode. The coding side (German).


Very nice work @Nordrunner, thanks so much for sharing!

@cristianhumelnicu do you have an example of a casing for the BME280 that can be used outdoor and will protect the BME from condensing situations?

Something like this…

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But that only prevents rain intrusion and direct sunlight influencing the temperature measurement right? It does not prevent condensation in the electronics housing, since you have to keep that open for the barometric reading and humidity measurement…

Have you looked at the SHT31 and Si7021 sensors with membrane/PTFE filter?
The versions with membrane/PTFE filter are rated for IP67.

SHT31 was previously mentioned in: The WORKBENCH part 1



Sensor modules based on Si7021 with filter are available on AliExpress:

A possible option to protect the rest of the electronics from moist and water is by covering (painting or spraying) it with (the sensor itself should not be covered of course):

  • Liquid Electrical Tape (LET)
    Manufacturers: Star brite, Permatex, Performix.

  • Plasti DIP
    Similar to LET (but possibly thicker).
    For electronics a thin layer better preserves cooling properties.

    Performix and Plasti DIP also have spray versions.

For reliable measurements you will still need a proper housing that protects the sensor from rain and (direct) sun light and that allows for sufficient ventilation. E.g. something like:

A compact DIY outdoor weather station could be build with a Heltec CubeCell HTCC-AB01 board + Si7021 module + BMP280 module and above plastic outer shield. The CubeCell board supports Li-ion/LiPo batteries and solar panel charging and uses only 8.5 uA in deep sleep when powered by Li-ion or LiPo battery.

Sensor Tests

Some tests with above sensors:

All humidity sensors measuring envinroment , so if is a high condensing medium , relative humidity will be 100% , and that will be measure

@cristianhumelnicu the point is that the BME280 breaks down in condensing environments. We experienced that one of our climate sensors, used outdoors, broke down after 6 months. The temperature reading of the BME was still OK, but both humidity and air pressure were way off and giving strange values. We were surprised by this but started googling and found out that it is a know problem for the Bosch sensor: It doesn’t handle condensing environments well, and that’s basically any outdoor environment in our sometimes humid and cold Western Europe climate.
So I am trying to find a practical and simple way to protect the BME from condensation, without disrupting the humidity or air pressure measurements. Have not found anything yet…

@rharte Don’t use bosch go to Sensirion

There is probably not an easy solution and it may be easier to use a different sensor that is designed for use in wet/condensing environments.

One hint for possible cheap solution to protect BME280 sensor is a thread seal tape but not for professional use!

Do you know if the same is true for the Bosch BMP280 barometric pressure sensor?

According to some articles and my own experience (disclaimer: based on sensors bought via AliExpress): BME280 and BMP280 often report too high temperatures and appear not to be designed for absolute temperature accuracy.