Hello Harry,
HB> I have my R Pi 3 B+ on my LAN, with latest NOOBS, setup to download HB> weather via USB from my weather station and present it as a webpage.
NOOBS is only interesting to get and to test the first feeling of an OS. For daily use it is to small configured and many things missing. So use the OS of your choice, and download that image to install. NOOBS can be used to look at different OSes, but it is incomplete compaired to the officiel release of each OS in a production environment. So do not use NOOBS for a serious task or server.
HB> During the early hours, I have the Pi configured to do a reboot and
How did you configure that? Because also I want to learn from it for later use.
HB> reload the software for the weather - that works fine.
HB> What I have found, is that if I also reboot via the GUI reboot option, HB> it also loads the weather interface software and it carries on as HB> normal
That seems normal.
HB> If instead, I type at the command line 'reboot', it doesn't reload the HB> weather software. I have to manually load it all in.
May be you have to logout first, and then do a SUDO reboot?
You know the difference of a warm boot and a cold boot? Another solution could be using a timeclock witch cuts the 230 Vac~ for only one minute a day at a choosen time at night. Just before that time clock reset cuts the power down, do a shutdown. Cutting power without shutting down can give problems later. When you configure you app starting at boot, it will start again normally when the time clock reset is ready and normal power given back again. I had to do this with my then unstable DOS BBSystem machine once a day. Good luck.
Henri.