Negative data not shown about dew point graph (weather)

Marco Zonca

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Dec 26, 2025, 3:56:18 PM12/26/25

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Hi,
A few days ago I started sending APRS data from my weather station. I noticed that the negative data calculated for the "dew point" in the temperature graph isn't displayed (as shown in the image below). I checked another nearby station and the result is the same...

Marco Zonca

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Dec 30, 2025, 3:56:14 PM12/30/25

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...so I think the aprs.fi weather webpage showing the graph should be able to show even negative dew point values. Can anyone modify that webpage when possible please? Of course it nothing serious but would be nice. Thank you. :-)

Heikki Hannikainen

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Dec 30, 2025, 5:24:08 PM12/30/25

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On Thu, 25 Dec 2025, Marco Zonca wrote:

> Hi,
> A few days ago I started sending APRS data from my weather station. I noticed that the negative data calculated for the "dew point" in the
> temperature graph isn't displayed (as shown in the image below). I checked another nearby station and the result is the same...

Hi,

aprs.fi was using an algorithm for estimation of dew point which wasn't
good for temperatures below 0°C. I've updated the algorithm to a better
one now, and dew point for freezing temperatures is now shown.

- Hessu

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