Yeah... There's a bug in rainmeter (version 0.14) with the week measure. It measures the week number, and subtracts 1 from it. So the range is 00-52 instead of 01-53.
Anyway. It's just a small fix, but it's on request from TheAslan, so here it is.
And those using the calendar but can't be botherd to download 1.03, you can just change the code yourselves.
Look for the [MeasureWeek1], then replace that entire section with this:
;%U is for sunday as first day of the week, %W is with monday as first day.
That fixes the problem.