There are a couple of things going on here.
First, you don’t have check-fetch-times.php installed on your site, so my remote diagnostic ability is very much reduced … please upload that file from the Base-Canada distribution.
Second, I did a view-source of the wxradar.php page (using wxradar.php?cache=no to force a cache reload) and found
It looks like attempts to get the detailed images from meteo.gc.ca were unsuccessful, and no headers were returned … since it happened repeatedly with < 1 second responses, I suspect that the meteo.gc.ca site was blocking those requests from the ip address of your webserver OR your PHP doesn’t have allow_url_fopen = on in your php.ini. It’s odd because the curl page request
worked, and the file was cached.
So, without other diagnostic tools available, I’m guessing that your PHP needs
allow_url_fopen = on
in your php.ini.