Can Rain Affect Wind Readings - Looks like Frost can as well (Updated)

I’ve been monitoring my weather data pretty closely during Florence and one thing I am noticing is the wind gusts were reporting higher before it started raining. Now that the rain is here, the wind reports are lower but I’m out on my porch observing and the true wind gusts are just as high or higher visibly. So my question is can rain affect the wind readings by limiting the amount of ‘air/wind’ flowing across the sensors?
Has anyone else noticed this?

If water droplets are interrupting the sonic paths, then yes rain can affect the wind readings. The most common cause of this would be water droplets forming on the sonic plates.

I should add that WeatherFlow use filters to remove the erroneous wind data. It’s a possibility that the strongest gusts happen to coincide with when the wind readings are most contaminated by the heavy rainfall, and therefore are being filtered out.


Yes that sounds like a possibility…and with a hard blowing rain, I’m sure that can give the rain and wind sensors a real challenge.

Rain definitely affects how the sonic transducers read wind directions and speed when it collects on or around the plates. The measurements will return to normal after the area dries. I’ve had small thunderstorms here with 10-15mph wind gust blow rain droplets on the plates. Wind measurements end up registering up to 60mph from all directions. WeatherFlow is working to help solve this problem as best they can so let’s just give them some time.

After the rains, I climb the mount to use a paper towel and gently soak up the rain droplets around the plates and wind path to help calm wind measurements back to normal.

there is a solution for this and doesnt require firmware filtering . i started something many months ago but i seem to get preoccupied and forget to publish my findings . i added some very fine plastic thin mesh , i cut it to a slightly larger diameter and place those over the four transducers holes my initial findings were good no wind drop outs during heavy rainfall unfortunately i never took it any further or did any more probably some other teething issue arised and i put it to one side. the idea was after studying how more expensive wind sonic products try to deal with it. not all do it some use a plastic dome shape cover to allow rain splashes to roll and some use a simple plastic thin grill mesh type . i mean very thin ,… a google search on sonic transducers will return many different approaches thats where i found it and initial tests proved ok … beauty of it if your prepared to experiment you are not taking apart or dismantling the product your simply placing a small mesh over the transducers… whilst its not 100% proof of eliminating water splashes but certainly reduces chances of build up …note small mesh gauge …image


I experienced it this evening.
There wasn’t that much wind as earlier this day.
But the Sky came up with a gust of 42 km/h in a shower. Think some water came onto the sonic transducers?

First time I’m seeing this. :slightly_smiling_face:

Strange wind readings this night and this morning.
Gusts from over the 30 km/h when the trees where barely moving.
Odd peaks in my wind dashboard and completely wrong wind direction. Like it was stuck on SE direction.
It occurred after a verry heavy rainstorm with big winds.

Untill the station got offline. After rebooting all was normal again. I know my Sky isn’t in the most ideal spot. But it gives the wind direction fairly good.

Your R&D efforts continue to amaze and impress, Brian! Mesh over the transducer may indeed inhibit water droplet attachment. However, that’s actually a much less common issue than the main issue with rain, which is rain drops settling on the reflective plate. Any object in the path between transducers will affect the reading. Normally, rain is blown off quickly and it’s a non-issue. Occasionally, raindrops form a puddle on the plate and, in calm conditions, stays put.

Fortunately, this is something that’s pretty straightforward to identify and handle in firmware. The increase in reports of this issue after the release of v94 lead me to suspect we may have inadvertently caused this issue to become more prevalent. We’ll dig into the data this week and see what it says…

That is one way the issue presents itself, indeed. We’ll look at your data and hopefully it will tell us what’s going on.


i wouldnt call it r&d call it curiosity or just shear stupidity sometimes you win sometimes you dont. anyway i have a spare SKY or 2 with fully working wind so let me confirm when i get the chance , what is the significant importance of plate distance to transducers i.e gap between plate and head unit. ps…i fixed the wireless strength isuue …:grin:

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It was a peak just right after midnight.
Sky was stuck on a SE wind. But the real direction was SW. It had some unexplainable high peaks in it.

Curious if can make something out of my data.:slightly_smiling_face:
After that it looked like sky and air weren’t reporting anymore… … they did, but the app said 6 hours ago.

Rebooted and everything was back no normal.

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We had some wild weather here, last week. An active cold front producing squally winds and heavy rain was on it’s way… for hours I had a consistent SW being recorded on both my Davis and WF station, so all was good. A lot of rain fell in a short space of time, it didn’t affect my wind speed readings, though. As soon as the cold front had passed, the wind immediately changed to a direct Westerly on the Davis, but not the WF. The WF station was recording NW to NE winds, it wasn’t until about 6 hours later that it reverted to the actual Westerly that was occurring. A couple of days later, more rain, and it did it again. It was showing virtually every compass point, accept the correct one. Once again, it corrected itself after several hours.

PS: On the 20th, winds were gusting 40 to 50mph with a wind speed of 25mph. I was regularly seeing 30mph+ gusts on the Sky unit and then suddenly a drop to zero with a bearing of North, when clearly it was still blowing pretty hard. This has a knock-on effect with the ‘gusting’ text on the dashboard. Instead of saying 15 - 30mph, it was showing 0 - 30mph rather a lot.

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I have some ceramic nanocoating I’ve put on my car. The water beads very nicely, even on plastic. I could put some on at least the lower surface of the wind gap if it won’t adversely affect the readings. Of course we may not know if it helps until we get more blustery weather. Since both of my stations are usually next to each other I could treat one and leave the other to see if it makes any difference. Once it is on, however, it is permanent.

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I would like to invite you to take a look at my station currently if you have time! We had some rain last night, but the wind readings this morning are all over the place and it has been perfectly still all morning. According to the data, it hasn’t rained since 2am. I guess it will continue to behave like this until it dries out or something?

Yes, this distance is critical.

Yes, it looks like this was the “rain-on-plate” issue.

Another case of rain-on-plate for sure.

This was most likely NOT due to rain-on-plate - we need to do more analysis on this one.

Go for it! The coating itself won’t affect the reading. We are testing a couple different hydrophillic coatings that show some real promise for mitigating the rain-on-plate issue.

Definitely rain-on-plate!


Thought so… The storm we had before it occurred had some extreme rain and wind.
Glad you could catch that one @dsj
Last days all is working excellent. Wind could be shifting when there isn’t much wind, because I am surrounded by houses.

Are you talking about something like RainX for car windows ?

No, I’m talking about a ceramic nano coating, specifically It is very hard and won’t wear off for a long time, probably will last for ever on the SKY. It isn’t cheap but it works great on my cars and RV.


RainX is hydrophobic, which repels water but also causes larger beads, which exacerbates the issue. The stuff we’re testing is hydrophillic, which causes water beads to flatten out - shedding rather than beading. In theory that will keep water from significantly affecting the length of the path taken by the ultrasonic signal. Initial testing is promising… Check out this video:


Do you plan a kit to ship to the owners to self-coat the delivered Skys ?

I suppose, the key issue would be, the bottom (maybe as well the top) surface should remain as flat as posssible ?
Did you think about a (nano) structured surface ?
At which wavelength are the ultra sound transducers operating ?

Will the hydrophillic coating combat my Sky’s biggest challenge?



FWIW, this is the Sky that sits on the deck rail next to the VP2’s tipping bucket and Stratus, and is only being used for rainfall measurements and not wind…

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If we find a coating that’s effective, we’ll work out a factory process for applying it during future production runs. For current owners for whom this is a significant issue, contact us directly and work out an appropriate solution.

That’s an interesting idea we have not considered. The transducers operate at 40kHz.

Actually, it might. Another property of this coating is biologic anti-fouling.