Might be time for you to start a new thread specifically for your forecast problems, I think this one is getting a bit long and you now have a new issue.
You might like to start off by stopping WeeWX, confirming
debug = 1 in
weewx.conf, deleting the forecast database
forecast.sdb and then restarting WeeWX. Let WeeWX run for 2-3 archive periods and post a log extract from when WeeWX was restarted until the 2-3 archive periods have elapsed. Would also help if you posted a
wee_debug report. Make sure before posting the
wee_debug report you check the output for any user names, passwords or other sensitive data and remove before posting.
wee_debug does a good job at doing this but its not perfect.