Outdoor Humidity Sensors


I’m looking for an Outdoor Humidity sensor to connect to my emonPi2. The emonTH is a great unit for indoor and there is an outdoor temp sensor available, but no outdoor humidity sensor.

Wondering what everyone else is using to capture outdoor humidity.


I have an Ecowitt weather station, integrated with Home Assistant which pushes the data to my emonCMS. A bit circuitous but it works and was designed for outside.

The emonTH should work in an undercover sheltered location to measure outside humidity.

Hi Christian,

thanks for the suggestion. I am familiar with Ecowitt as I use it for monitoring soil moisture primarily. I was looking for a simpler “plug 'n play” solution similar to the emon TH that I could connect to an emonBase or emonPi2.

I will keep looking.


I am concerned about moisture from rain and snow corroding the device even under an eaves and wonder if too much of a shelter would impact humidity readings much.

Have also been thinking about spraying the emonTH board with a conformal coating to see if that would protect it, but not sure if this would cover the humidity sensor and thereby make it ineffective.

Still searching.


I have used an emonTH outside; initially in an open cabinet housing my solar inverters, then in a waterproof electrical junction box.

I did get varying humidity readings from inside the junction box but I don’t know how accurately they can reflect the true humidity outside the box as it was supposed to be waterproof.

I also put an emonTH inside a freezer and it stopped working at about -20c. It worked normally after thawing out. It may have been the battery rather than the emonTH which stopped working in this case.

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I have one of my TH units in my external meter box. The readings seem fine and relative to both the ones I have indoors and in the garage.

The external one has an external temp probe as well as the built in one. They are normally fairly similar but the one in the unit heats up noticeably when I’m pulling 20kW or so overnight charging the cars, battery etc. Shows how warm 25mm tails can get.

Not one to give up, I found a solar shield on AliExpress that I modified slightly and now have the emonTH inserted inside. If you are interested, they sell them by the “floor”, and I found that 7 floors are the right height to enclose the emonTH. Cost was around $25USD shipped to me.

emonTH Inserted
emonTH assembled
emonTH Housing

I am going to place it outside for summer, fall, winter season to see how it fares.



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It ought to hold up well.

Other forum users have done the same thing, with good results.


Those Screwfix ones are completely sealed, so no good if humidity readings are needed (which the user there states, no sensor is fitted).

Robert, you are correct. I need humidity readings as well as temperature.