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Humidity Maxes Out at 98%

Discussion specific to Davis weather stations
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krmidas
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Humidity Maxes Out at 98%

Post by krmidas »

Has anyone else had this issue with their VP2? The odd thing is, several years ago, I used to see 100% humidity readings.

I just had my T/H sensor replaced, we'll see if that makes a difference.

-Tom
Last edited by krmidas on Tue 29 Oct 2019 9:28 pm, edited 1 time in total.
Tom Keramidas, Lake Zurich, IL, USA
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beteljuice
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Re: Humidity Maxes Out at 98%

Post by beteljuice »

I didn't think there were any sensors that achieved 100% unless they were under water ?

Don't I remember a 'setting' somewhere to treat 98% as 100% - there is in Cumulus if not in your console.
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Mapantz
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Re: Humidity Maxes Out at 98%

Post by Mapantz »

I have gotten 99% on my VP2 on several occasions, never 100% though - not really bothered me.

CMX also has the option to treat 98% as 100%. :)
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krmidas
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Re: Humidity Maxes Out at 98%

Post by krmidas »

beteljuice wrote: Mon 28 Oct 2019 9:18 pm I didn't think there were any sensors that achieved 100% unless they were under water ?

Don't I remember a 'setting' somewhere to treat 98% as 100% - there is in Cumulus if not in your console.
There is a setting, but it seems intended for Oregon Scientific stations (according to Cumulus help).

The odd thing is I used to occasionally see 100% (several times a year), but for around the last 6+ years, nothing. My station and my software haven't changed. Always struck me as odd
Tom Keramidas, Lake Zurich, IL, USA
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beteljuice
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Re: Humidity Maxes Out at 98%

Post by beteljuice »

It CAN also be done at the Davis console.

From ProData website:
The sensor will still likely be operating within its accuracy specification, which is typically ±3%, if not greater, close to 100%;

Conditions of genuine 100% RH are relatively uncommon except in continuous thick fog – a rain shower or even longer periods of rain won’t necessarily give RH approaching 100%;

Even if the sensor won’t quite achieve a 100% reading, the chances are that it is operating within its specified accuracy at all lower RH values – any error in the reading close to 100% RH is not representative of accuracy over 10-90%;

Note: It is possible to enter a humidity offset into the console to force the maximum RH reading to 100%, but this really isn’t recommended – it will create very significant errors in RH readings in the mid-range of humidity.
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