curl -s http://weewx.com/keys.html | sudo apt-key add -
curl -s http://weewx.com/apt/weewx-python3.list | sudo tee /etc/apt/sources.list.d/weewx.listFor python2 (debian9 and earlier):
curl -s http://weewx.com/apt/weewx-python2.list | sudo tee /etc/apt/sources.list.d/weewx.list
sudo apt-get update sudo apt-get install weewx