Dear cmgc and WeatherCat troubleshooters,
No as I see it it is only the rainfall.
When I look at the data viewer/editor window it starts each day at about 00.02 . After the 26th it starts at 01.02 and the rainfall seems to reset at 01.00 hrs but this seems to produce some doubling up of volumes and other odd data numbers in the raw data file while it settles down? I assume it is just a case of doing the daily calculation.
The clocks on the mac/ the console and weathercat all read in BST as is correct.
Unfortunately, all I can admit is puzzlement. Okay, I assume you are somewhere in the British isles since you are taking about British Summer Time. It turns out that Stuart Ball (WeatherCat developer) is based near London, so there is no way that the software could have a regional flaw without him noticing it immediately.
WeatherCat simply reads the Davis Console retrieve rainfall data. So it is possible that your console is malfunctioning even it the time is correctly set on the console. You might try reaching out of Davis technical support. I don't know how you do that from your location. You might search the Davis website to see what technical support options you have:
https://www.davisnet.com/Sorry, but you do have an extremely peculiar problem and that's all I can imagine at the moment.
Edouard