Pressure in inHg to 2 decimals?

I’m used to seeing barometric pressure expressed as inHg to 2 decimal places: ie. 29.92. The display in the WeatherFlow app is more accurate: ie. 29.923. Is there a way to display the baro to only 2 decimal places?

Regarding the lightning sensor, I’ve tried moving the Air device in 90 degree increments through 270 degrees and I still get false readings. It may be that the device will self learn or auto calibrate but so far, the lightning sensor is the least reliable readout in the app.

Are you asking for an option to display values at reduced precision? But to answer your question, no, you cannot do this in the app.

Regarding the lightning sensor, you might just have a noisy environment. Try relocating the AIR unit away from EMG sources if that is a feasible option. You may have reviewed the help pages already but if not, here is a link to troubleshooting sensor readings:

Thanks, I previously reviewed information you linked to.

On the baro question, in aviation the commonly accepted way of presenting inHg measurements is XX.XX - there’s no other way to set an altimeter in an airplane. In my 40 years of flying I’ve never seen XX.XXX . Things may be different for weather aficionados.

I appreciate you taking the time to respond.

Hi, you’re very welcome. You can just round the number to set your altimeter.
29.923 ≈ 29.92
29.927 ≈ 29.93

I hope this helps!


I had asked this question once before too. In meteorology, it’s far more typical to see barometric readings going out to 2 decimal places, not 3. Although you may get greater precision going out to 3 decimal places, the stated accuracy of the barometric measuring device is only .03". So, at least IMO, the added ‘precision’ can be a bit misleading. If the stated accuracy of the unit was .003", I could see going out that extra decimal place. You should be aware that many feel quite differently from you and I. :wink:

All in all, it’s something I’d like to see as a future user setting, but I guess there area bigger fish to fry. :slight_smile:

I agree. In this case, XX.XXX inHg is just odd. It would be nice if WF gave the end user the ability to better tailor the display but they don’t seem particularly responsive to this. While I understand WF wanting to be precise this just seems like something an engineer decided to do without regard to real world practice.

All in all, however, WF has more responsive customer service than their competitors and the PWS is an elegant piece of kit. I’m looking forward to see how they refine it and what additional features they add in the future.


Absolutely. When I put this all in to the context of how responsive the WF team is, and how rare that it is with today’s consumer electronics, it’s not really a big deal.

Isn’t the precision ±0.03 but the difference precision is higher? If this is the case it makes sense to display to 3 decimals for comparative analysis. That being said, I wish the displayed precision didn’t change when the last digit is zero.


The precision is to tenths xxxx.x in millibars.

1 millibar is 0.0295 inHG so it makes sense to display to three decimals.


For those of us who have given up measurement systems based on the foot size of a long-dead king, this is not an issue. The pressure in millibars is only displayed out to one decimal place…


Actually the international buro of units sets “Pa” for pressure. Hence for the use case atmospheric pressure “hPa”, which is deci-proportional to mbar is the prefered unit.
So the precision makes sense, as the sensor is able to deliver.

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It is clear that our declaration of independence failed to include units of measure. :frowning_face:


It really is amazing that we did not wind up using the French Republican Calendar, given how the French backing of the revolution was influential in our victory and with Benjamin Franklin spending almost 10 years in Paris right before that as Ambassador to France.

Nerd alert - My foot in the official public reference for one foot, outside the British Royal Observatory in Greenwich…



Any respectable scientist would use SI: there is no room for discussion on that:-)
My elderly Fortin does 2dp in inches!


By which I mean that three is pointless; you get to the stage where you are measuring whether somebody has slammed a door in the same room. Same Fortin does cm to 2 dp, because it can! It’s actually a test of eyesight at that level!

the stated relative accuracy is 0.003" or 0.1 mbar, so it makes sense. In millibar it feels perfectly normal to have 1 decimal, translated to inches it might look a bit unusual, but you do get accurately the small changes in pressure.

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Yup. If the stated accuracy is +/-.03”, then if the actual pressure is 29.95”, the Air will be in tolerance with readings between 29.92”-29.98”. So I can’t see the merit in having readings out to 3 decimals when reading out in inches of Hg.

I’ve never seen a weather service stating a barometric pressure of say, 29.957”. I know there are instruments that do readout to 3 decimals, but their stated accuracy is better.

But as I said, there are those that feel one way or the other.

indeed if the air pressure is 29.957 the actual pressure might be 29.927. but then it will not show 29.987 with the next measurement or any time soon (when actual air pressure doesn’t change) because the relative accuracy is only 0.003". It might fluctuate by that little amount.

If the real air pressure rises 0.003 you should notice it. If the air pressure for example raises every 30 minutes by 0.00333, you would see a sequence like
29.957 29.960 29.963 29.967 29.970 29.973 … all very accurate relative to your first measurement of 29.957. They might all be off by 0.03", but the relative difference is accurate and you might conclude that pressure is on the rise.
If these values are rounded to two decimals it looks like
29.96 29.96 29.96 29.97 29.97 29.97 which cannot lead to any accurate conclusion about the trend as for these measurements the real air pressure might have been
29.963 29.965 29.965 29.967 29.966 29.966 and you would have gotten the same rounded numbers and the difference is just noise.

of course the first sequence looks nicer in hPa or mBar.

edit: in addition if you would calibrate the device at some point in time to the exact value (which can easily be done after plenty of measurement that show for example that the pressure is always 0.03 too high), you will have a very accurate system that shows you the pressure with an absolute precision of 0.003. It might drift over time but re-calibrating often enough to compensate for a possible drift would solve that. That is exactly what weatherflow is doing.


Doing what you say would remove the ability for the more precise relative measurements as opposed to absolute measurements.

IMO a pressure change of .003" is essentially insignificant. Any kind of significant weather change will show a much greater pressure change. So yes, you might have somewhat greater ‘precision’, but for what?

We’ll agree to disagree as I think we’ve been around this block before, but I think there’s a reason why weather services (including the NWS here in the U.S.) don’t bother going out 3 decimals (when stating pressure in inches of Hg).