I have wrong dates showing up in my jQuery UI datepicker in some 2016 months in Firefox (Mobile & Web). For example:
March 31, 2016 is Thursday and April 1, 2016 of course is a Friday - but not on my calendar, where it shows up as a Thursday, as well. There is the same issue for May 2016.
Please see screenshots:
and 
Note that I tried to use many versions of jQuery scripts but have the same issue with all of them.