[RetroTechie]

Yep this is so extreme overkill... (as is common these days).

And a full-blown database, just to record some temperature readings?

Say you measure temps in 1-minute interval, 24/7. That's what, a few KB of data/day? Even a lowly uC could keep that in RAM, and/or write to internal flash. No database - just raw data written to memory locations, circular buffer style.

When checking (over WiFi eg.), ask uC to cough up those readings, and use whatever tools desired on laptop/PC/whatever, to turn them into pretty graphs.

Cause of 'issues' here = making things more complicated than the simple things they are.

Btw: can't imagine a ready-made solution couldn't be found here? Logging temps & checking those over a LAN must have been done (+published!) a 1000 times before.