Everything looks OK with weewx on the Pi 3 B+.
I did a fresh install of Raspbian Stretch from a full NOOBS setup, then loaded weewx using the instructions here:
http://weewx.com/docs/debian.htmUsing the weewx defaults and running the simulator, everything seems to come up fine.
The only problems I ran into weren't weewx related.
The power supply I've been using wimped out on me, and the Stretch installation would fail at about 17%. I could tell I was having power issues because of the "lightning bolt" that would appear from time to time on the desktop. Using a beefier power supply fixed that problem.
Setting up the WiFi took a little longer than usual as you now have to set the country code for WiFi in raspi-conf.
Otherwise, setup of the Pi and weewx was typical.