I am assuming that the WU page on your Mac displays correctly?
Can you try a different browser on the iPad?
The point would be to
try to get WU to send a regular html document rather than one for what they think should for a "mobile" device. I'll try your page on my very old iPad...
Looks like it works fine for me. Here is the Weekly Precip graph (didn't send the others to save space on the forums). BTW, it appears your "week" starts on a Monday?

My only suggestion is to shut down Safari completely (not just put it in the background). If that does not help, you might try to delete the Safari History in Settings.