SHT-30 Mesh-protected Weather-proof Temperature/Humidity Sensor - 1M Cable (ADA4099)

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Take your next outdoor sensor project to the next level with this SHT-30 based temperature/humidity sensor. The sensor includes a dual-use sensor module from Sensirion … read more

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Hi, I was wondering what is the diameter of the cable for this particular product SHT-30 Mesh-protected Weather-proof Temperature/Humidity Sensor - 1M Cable ADA4099


Hi Mohan,

Welcome to the forum :slightly_smiling_face:

We don’t have any stock of those sensors on the shelf at the moment so I can’t measure one up for you today but I’ll make a note to have them measured when we next get some.

For now, you can estimate the cable diameter roughly using the product scale photo with the American Quarter. Wikipedia tells me that a quarter dollar has a diameter of 24.26 mm


Have one of these on order. The waterproof claim is what I am after. Every other temp/humid sensor I looked at needs protection from moisture to work correctly.

It will be used in a watering system controller to sense environmental conditions in an effort to reduce water wastage. Even so it will need protection from direct sunlight, as that would really upset the readings. Weather stations use radiation shields to accurately sense temp/humid.

I am hoping the sensor will detect humidity more accurately than the other cheaper ones I have played with.



@Mohan192545 Received this product today. See cable diameter measurements below.


Hi Jim,

Thanks heaps for sending those measurements through! I’ve updated the product page with the new measurements.



Hi everybody,

I am not too happy with the humidity reading of this sensor. It is accurate but it is offset by +20% (reads 100% when it is actually 80%). I’m wondering if there is some other kind of calibration I can do. Other than an offset…

I have been testing this, an SCD-41 and a BME280 against a very high quality Testo humidity probe. They now all read very accurately and agree with the Testo.

  • The SCD-41 has been bang on with the testo
  • The BME280 needed +5% offset.
  • The SHT-30 needed -20% offset.

Because of the -20% offset, the SHT-30 now only reads up to 80% humidity. It is accurate until then but above 80% it just flat lines. The SCD-41 and BME280 keep measuring up to 100%. I am planning to use this mesh-protected SHT-30 as a soil temp/humidity sensor. I would really like that last 20% of relative humidity measurement.

I am using it on an esp8266 through esphome on homeassistant. Applied the offset filter in esphome. Here’s the code:

     sda: D2
     scl: D1

  - platform: sht3xd
      name: "Soil Temperature"
      force_update: true
      accuracy_decimals: 2
      name: "Soil Humidity"
      force_update: true
      accuracy_decimals: 2
        - offset: -18
    address: 0x44
    update_interval: 10s    

This was the initial test. You can see the SHT is 20% higher.

Here you can see it reach 100% while thev SCD-41 is still around 80%. Measures all the way up to 99% while the SHT has been flatlining.

Now I put it in the dirt and as you can see, it is flatlining at 82% (I changed the offset to -18). Maximum humidity I can read with this SHT-30 is 82%. It would be great to have that last 18%…


Nothing stands out why it would be sensing differently. Nice graphs btw!

There is a review for the product that suggests it works well in the regions you can not. Is it possible the mesh has been submerged or exposed to liquid and it’s now reading differently than expected? Might be worth comparing with another SHT-30

This sensor has been running perfectly (spring/summer) and is much better with humidities around 90%-100% than the DHT22.


I like graphs!

I tested it without the mesh. Same readings.

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Ok - though if it was already submerged or exposed to liquid then it might not be coming back from that. Not saying that you did, though nothing in the comms says otherwise.

Comparing with another SHT-30 would probably be the best way to confirm. Prototyping & testing; always get two!


All testing was done before contaminating the sensor in any way. It’s only now that I’ve confirmed all my readings that I’ve put it in the dirt anyway. I’ve never used a soil humidity sensor so I was hoping humidity may be in a range below 80%.

I’ll probably buy another in future. It is a very nice sensor if you don’t need to measure above 80%RH. Little pricey to splash out for purely for testing… I might have a look at squeezing a different sensor in the mesh housing. The housing is very nice.


Hi Kris and All
All very interesting. As a matter of interest how are you testing these things. Do you have an environmental chamber at your disposal.

One thing that I don’t get is how can a humidity sensor be “moisture proof”, after all it is the moisture in the air the device is measuring. Reading the description re the mesh keeping out water but allowing air to pass and be measured I assume the device is proof against “condensing” moisture, that is water droplets condensed on the sensor.

I quote from the description
“While it is designed to be submersible in water, it’s always best to avoid long-term submersion (over 1 hour at a time), and it obviously would only give you temperature readings. For that, Adafruit’s metal-cased temperature sensors would be better! This sensor is best for simply placing outside for exterior weather sensing.”
with emphasis on
“and it obviously would only give you temperature readings”
which implies that the device will not read humidity while water is preventing air circulation, which is fair enough.

I think it would be fair to say that having this device buried in soil would be pretty close to being immersed in water. Not restricting air to the same extent maybe but pretty close so personally I don’t think this device would be designed as a soil moisture measuring thing.
Just a thought
Cheers Bob


Hi all
What happened to this conversation?? Did the mention of an environmental chamber frighten everybody off.

I will try to explain where I was coming from.
Comparing different sensors. You can compare apples with oranges until the cows come home but the whole exercise will mean little without a known device.
The only way I think to evaluate these things is to expose them to a known environment and the only way I know to do this would be with the aforesaid chamber. Unfortunately not usually readily available to the home constructor or hobbyist. They usually just have to believe the numbers that come out of the sensors in use.

I think the only way the home hobbyist would have to get an idea of performance would be to

  1. Take the unit into a room where an air conditioner has been running for a few hours. You would expect the humidity to be quite low. you won’t know exactly how low but may get some idea…
  2. Take the device outside on a very foggy day. I believe thick fog is regarded as close to 100% so this would give an idea at the other end of the scale.
  3. Compare it with a wet and dry bulb measurement. This could be easier said than done as with the advent of the modern sensor these instruments seem to have disappeared. BUT, in the absence of a controlled environment this would be the best way to evaluate a device. Better than trying to compare with other units of mostly unknown performance. One of these things maybe could be found in an antique shop which leans toward old technical stuff.
    Cheers Bob
    Add on.
    I just Googled “wet and dry bulb” and it seems you can still buy these devices, even on E-Bay.
    I also note the better digital units cost sometimes a figure well north of $1k. I think even some of these use the wet and dry bulb principle but provide a digital read out of humidity and dew point.

Hey mate sorry I never got back here. Thanks for taking time to reply.

Testing was done in a small, climate controlled tent. Can call that an environmental chamber…

Tested against a very high quality Testo branded sensor. I’m a HVAC technician by trade so have professional quality tools.

Humidity is 20% out for whatever reason. Ended up putting a -20% offset on the sensor and calling it a day.

Useless as a soil sensor in case any one else is wondering…

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Hi Kris

Probably about as close to an environmental chamber you will get easily easily and without a LOT of dollars.

Pleased someone verified my thoughts on that.
Thanks for letting us know the outcome.
Cheers Bob


I believe the problem is that once the dew point is reached condensation forms on the humidity sensor. Once it is water logged the sensor will give incorrect readings. This will persist until the sensor dries out and this can take some time depending on environment. A sensor continuously exposed to high humidity can be permanently damaged.
Anecdotally I have heard that some sensors are better with high humidity than others with the BME280 amongst the best and the DHT22 the worst.
For the SHT-30 the datasheet states the recomended humidity range is 20-80% and humidity >80% will produce an offset. It warns that while the sensor will recover prolonged exposure to high humidity “may accelerate ageing”. An accurate humidity reading requires good air circulation so I find the concept of a weather proof sensor a contradiction.
So for measuring high humidity a traditional wet and dry bulb thermometer or the newer heated probe is needed, but these are expensive.

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