Last-minute theory re Harry's birthday

[Kirstini]

No: HPFGUIDX 61269

Terry , after some great theorizing, wrote:
Is Harry specifically vulnerable on his birthday?  And if so, why?

Kirstini:
Hey Terry. I believe there has been an earlier post, not on this 
precise topic, but on the use of specific dates in the series. I 
believe that, in addition to Harry's parent's murder on Halloween, 
July 31st (Harry's birthday) was also identified as a witching 
Sabbath. Can't remember the exact significance of the dates just 
now, but this could tie in quite nicely with your theory. Of course, 
JKR was also born on July the 31st, and gave Harry her 
birthday...but never mind that just now >g<. 
Kirstini, whose boyfriend was also born on July the 31st, 1980...