Humidity tuning

So as Gary suggested, I moved the Air off the table and put it on the dry rubber landing of an absolutely dry ladder I brought outside for this purpose. As you can see from these screenshots, the Air dropped only a couple of percent and remained much too high throughout the night.

The accompanying screenshot shows the PWS in my area (including my Davis in the center). The Air is reading roughly 15% too high and seems unable to shed its moisture. This isn’t the first time I’ve seen this behavior. I also included a shot of the temperatures in my area and with my Air (28.6) sitting at 2-3 degrees below my VP2 and all other PWS in my area, that doesn’t help the RH reading.

It’s time to bring in the support techs. Send an email to and reference your last post.

Yes, thanks, will do Gary.

Just an update: My Davis is currently reading 39% which is in the ballpark of trusted PWS in my area. The area NWS locations are reporting 42% & 43%. Yet my Air is reporting 60%. That’s a very large delta and one that’s actually been getting somewhat worse. So I’m not sure what’s going on. :frowning:

Hi Ken. That lag is definitely not normal. Since you’ve ruled out the idea that the wet table might be creating a hyper-local zone of high humidity, another possibility is that you’re AIR is somehow getting water up inside the sensor vent area (perhaps after splashing off the table during rainfall?). Do you think that’s possible?

If so, you may be able to resolve that by placing the AIR in a more sheltered area and/or a place where water is less likely to enter the vent.

It’s also possible you have a faulty RH sensor, though that usually presents in different ways.

Hi Dave. The Air, prior to moving it, was located on the table but raised several inches above on a mounting plate. I don’t think it’s likely that water splashed up into the unit, but I can’t be 100%. I just placed it back on the table for the purpose of showing you the mount it sits on (see pix below). I’ve also noticed some erratic behavior of the barometer, sometimes reading .11" high and other times quite close. I’m not sure what’s causing that and if it can somehow be related to the issue with RH.

I’m game for either replacing the Air unit or giving it more time to dry out, but as I pointed out above, the delta has actually increased, currently sitting at 17% as I write this. So if it’s a wet sensor, I’d expect the delta to decrease over time as opposed to the increase I’m seeing. I’ve also seen this same behavior before.


Thanks for the extra detail, Ken. We want to send you a new AIR and let you place it side-by-side with your current AIR. That should give us some good info! We’ll contact you directly to confirm your shipping address.

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Dave, thanks for the great support. I sent you the requested info. Looking forward to the A/B of the two Airs.


WeatherFlow has great support. One can’t ask for much more.


Is the patio umbrella keeping the humidity trapped near the table???

Actually we took the patio umbrella down in November. What you see there is just some pvc piping I had once used for my Sky installation before I moved it. I never brought that piping in.

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The relative humidity data are fairly good for my station, but it is noticeable that almost always shows a 2-3% higher value. I have a dry and wet thermometer so I can compare data from Air.

Last week for two days we had very wet, but not raining, conditions. Everything dripping wet, visibility of 1 mile or less. All surrounding stations showed 95% to 99% but mine peaked out at 82% humidity. Today is starting out the same way. At first I thought it was raining but everything just wet. Humidity reading 77% but again, all around me show 95% and up.

I have a similar problem with my station, it stays in a range of 70% +/-
My Vantage Pro2 shows humidity of up to 82% the WF there are no changes, I already reported to the technical service of WF but I have not had an answer.

I have noticed that since I put one of my Airs in the WF suggested Ambient radiation shield, my RH readings are much better. I could be wrong, but I really think the Air needs some kind of sheltering.

My other Air is not in a shelter and located only 2’ away from the sheltered one, and its readings can be really off. After a rain event, the unsheltered unit can take a number of hours before its humidity begins to drop whereas my VP2 and sheltered Air drop much more quickly.

I recently had a ‘problem’ with the moisture measurement. This suddenly increased from 30% to 99%. How can that be? What can I do to prevent this false measurement?WeatherFlowHumidityFailure

Hi folks. Anyone still having humidity issues, please contact and someone can take a deeper look. You may need a hardware replacement.

Several days ago I received Air replacement, WF was very fast with investigation and solution. Finally I mounted new AIR yestarday. Now, it seams that is working, humidity readings are similar/same like readings from not so far state observation points. Thank you WF!

Old AIR unit is moved to indoor with changed settings. Maybe it can help for some comparison.

Also, I discover that state meteorology observation unit in my area publicly share data about rain. My Sky is measuring more, hope that planned rain calibration will help to correct it (not just copy/paste from other station :-))) )

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As we’re coming to way nicer weather, humidity starts to swing here. Time to check it again against my Assmann Psychrometer (that I restored)

Well what can I say … spot on 53% for the SHT Air and same for the Psychrometer. Will take another point in late after noon when it goes up gain.

See how well the SHT Air is over the scale …


I’ve been seeing similar things with my Air. We’ve had a much wetter winter than usual in southern California so I didn’t think too much about this at first but lately the humidity readings seem to have lost connection with reality.
Here’s the overall history:

And then this is what happened yesterday:

Does this seem like something that requires a service request/replacement unit?