If you run check-fetch-times.php?show=versions on your site, it shows you have a few scripts to update to current versions.. one of them is the WU-forecast.php script .. that will get your WU-forecast working again.
If you only want to use WXSIM for your forecasts, then change Settings.php
$SITE['fcstscript'] = 'WU-forecast.php'; // Non-USA, Non-Canada Wunderground Forecast Script
$SITE['fcstorg'] = 'WU'; // set to 'WU' for WeatherUnderground
// Uncomment the two lines below to use WXSIM as the ONLY forecast script to use
// $SITE['fcstscript'] = 'plaintext-parser.php'; // WXSIM forecast (if only forecast script)
// $SITE['fcstorg'] = 'WXSIM'; // set to 'WXSIM' for WXSIM forecast
to
//$SITE['fcstscript'] = 'WU-forecast.php'; // Non-USA, Non-Canada Wunderground Forecast Script
//$SITE['fcstorg'] = 'WU'; // set to 'WU' for WeatherUnderground
// Uncomment the two lines below to use WXSIM as the ONLY forecast script to use
$SITE['fcstscript'] = 'plaintext-parser.php'; // WXSIM forecast (if only forecast script)
$SITE['fcstorg'] = 'WXSIM'; // set to 'WXSIM' for WXSIM forecast
and the WXSIM forecast will be shown on the dashboard and the wxforecast.php page.
It's still a good idea to keep the scripts updated to current levels