Ok, I'm looking at this from a different angle, and was wondering if 
someone knew the "right" way to do this before I go inventing a more 
complicated solution.

For Chill Hours, I just need to add up the time that the temp is below XX 
degrees between two dates. As I understand WeeWX, every database entry has 
the interval length and the average temp for that interval. So in theory I 
can query the DB for the number of entries between two timestamps where the 
temp is below XX, and multiply the number of entries by the interval 
duration (5 minutes default). 

However, that would have me doing that query every time I wanted to display 
the value, which might be unnecessary processing power. It would also limit 
my display options. For example, if I wanted a chart to show chill hours 
the same way rain can be shown (with a cumulative line, an absolute line, 
etc), I'd have to come up with a more complicated query. 

Which got me thinking, chill hours are somewhat similar to rain, in that 
they are additive. So do I just create a service that gets triggered on an 
archive entry, looks at the temp for that archive entry, and if the temp is 
below the threshold it adds a value to column 'chill_hours' equal to the 
interval duration is? Then instead of inches, I'm using "minutes" as the 
unit of measurement.

And is there any way to influence the daily summary table that would be 
created for this new "chill hours" field? Or do they all have to follow the 
same logic?

Am I going about this the entirely wrong way? Ultimately I'd like to create 
the ability to track the accumulated hours of various custom temp ranges, 
and use that data for charting similar to other existing fields. 

Thanks,
Seth





On Saturday, December 25, 2021 at 11:48:43 AM UTC-6 Seth Ratner wrote:

> Hi everyone,
>
> I was wondering if anyone had already come up with a way to monitor chill 
> hours (cumulative hours below 45℉) in WeeWx. I'm using Belchertown, and it 
> would be nice to have a readout with Oct-May chill hours, and maybe a chart 
> that shows the per-week and cumulative hours together. 
>
> Thanks!
> Seth
>

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